How do you write an introduction for a literature review?

Open with a statement that establishes why the topic matters — and if you use a statistic, cite a source you have opened and checked. Then define the scope and boundaries of your review, state your purpose explicitly, and preview how the review is organized. Avoid dictionary definitions and overly broad claims. As a drafting aid, many writers keep the introduction to roughly a tenth of the review; your programme's guidelines, not a rule of thumb, set the actual proportions.

How many sources should a literature review include?

There's no universal number—quality matters more than quantity. The published rules of thumb are few and they are explicitly rules of thumb: the Technological University of the Shannon library guide, for example, suggests 5–20 titles for an undergraduate review, 20 or more for an honours dissertation and 40 or more for a master's thesis, while telling you to check with your supervisor. No guide we could find states a doctoral figure. See the guide on how many sources a literature review needs for the guides behind those numbers and for the coverage tests that matter more. Your advisor or assignment brief sets the expectation for your context.

How do I avoid just summarizing sources instead of synthesizing them?

Organize by theme rather than by source. Instead of devoting a paragraph to each paper, group sources that address similar questions or reach similar conclusions. Use topic sentences that make claims about the literature as a whole, then cite multiple sources as evidence. Ask yourself: “What does the literature collectively say about X?” rather than “What does this individual paper say?” Synthesis means showing connections, patterns, and gaps across sources.

What's the difference between a literature review and a systematic review?

A traditional literature review provides a narrative synthesis of relevant research and allows for some flexibility in source selection. A systematic review follows a rigorous, pre-registered protocol with explicit inclusion criteria, comprehensive database searches, and often quantitative synthesis through meta-analysis. Systematic reviews are designed to minimize bias and are common in evidence-based fields like medicine. Most thesis and dissertation literature reviews are narrative rather than systematic.

Can I include sources that contradict each other?

Absolutely—in fact, you should. A good literature review acknowledges debates and conflicting findings rather than presenting a falsely unified picture. When sources disagree, your job is to analyze possible reasons for the disagreement, such as different methodologies, populations, time periods, or theoretical frameworks. This critical analysis of contradictions often reveals the gaps that justify new research.

How to Start a Literature Review: A Step-by-Step Guide

Starting a literature review can feel overwhelming—where do you even begin with thousands of potential sources? Whether you're working on a dissertation, thesis, or research proposal, the literature review is often the most time-consuming yet foundational part of your project. This guide breaks the process into steps, points you at five published open-access reviews you can read as models, and shows a worked synthesis paragraph built from three real papers you can check yourself.

What Is a Literature Review?

A literature review is a comprehensive survey of scholarly sources on a specific topic. Unlike an annotated bibliography (which lists and describes sources individually), a literature review synthesizes sources to show how they relate to each other and to your research question.

The chapter goes by different names depending on where you are studying, and the local rules differ with it: in the Philippines it is the review of related literature, or RRL; in Indonesia, tinjauan pustaka in Bab II of a skripsi; in India, the review of literature in a PhD synopsis. The method on this page applies to all of them; the format requirements come from your own faculty.

The Purdue Online Writing Lab defines it as "a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis)," and is explicit about the distinction that trips most people up: "Usually you will need to synthesize research rather than just summarizing it." It lists two things a review does for you — it helps you "familiarize [yourself] with a topic and with scholarship in [your] field," and it helps you "find gaps in existing research in order to propose new projects."

Literature reviews appear in several contexts: as a standalone assignment, as a chapter in a thesis or dissertation, or as a section in a research proposal or journal article.

The Purpose of a Literature Review

Understanding why you're writing a literature review helps you write it better. Key purposes include:

Establishing credibility: Demonstrating that you understand the existing scholarship positions you as a knowledgeable researcher.
Identifying gaps: By mapping what's known, you reveal what remains unexplored—which becomes the justification for your study.
Avoiding duplication: You don't want to "discover" something that's already well-established in the field.
Building a theoretical framework: The review helps you identify concepts, theories, and methodologies that will inform your own research.
Contextualizing your contribution: Your eventual findings will be measured against the baseline you establish here.

Types of Literature Reviews

Different research contexts call for different review approaches:

Type	Purpose	When to Use
Narrative/Traditional	Provides a broad overview of a topic	Course papers, thesis chapters, introductory sections
Systematic	Follows a rigorous, reproducible protocol to minimize bias	Evidence-based research, meta-analyses, clinical studies
Scoping	Maps the breadth of literature on an emerging topic	New research areas, policy reviews, identifying research gaps
Integrative	Synthesizes diverse methodologies to generate new frameworks	Theory development, cross-disciplinary research
Rapid	Accelerated synthesis for time-sensitive decisions	Policy briefings, preliminary research assessments

For most students working on theses, dissertations, or course papers, a narrative literature review is the appropriate choice. Systematic reviews follow a protocol that is written, and usually registered, in advance, and are reported under the PRISMA 2020 guideline. For a full comparison and a decision path, see systematic vs. scoping vs. narrative review.

Literature Review Outline Template

A clear structure is essential. Here's a flexible template that works for most literature reviews:

Standard Literature Review Outline

I. Introduction (10-15% of total length)

Define the topic and scope
State the purpose and significance
Provide an overview of the organization
Present your thesis or central argument

II. Body Sections (75-80% of total length)

Organize thematically, chronologically, or methodologically. For most topics, thematic organization works best:

Theme/Subtopic A

Summarize key findings from multiple sources
Identify points of agreement and disagreement
Note methodological approaches
Evaluate strengths and limitations

Theme/Subtopic B

(Same structure)

Theme/Subtopic C

(Same structure)

III. Conclusion/Discussion (10-15% of total length)

Summarize major findings across themes
Identify gaps in current knowledge
Explain how gaps connect to your research question
Suggest directions for future research

APA Literature Review Outline

When writing in APA format, use heading levels to organize your review. APA 7 has five levels; the first three are the ones a review usually needs, and their formats — as set out in the Purdue OWL's APA headings table, which reproduces the manual — are:

Level 1: centred, bold, title case
Level 2: flush left, bold, title case
Level 3: flush left, bold italic, title case

Always start at Level 1 and go down in order. The OWL adds two points that catch people out: in APA Style the introduction section never gets a heading, and the title of the paper counts as the Level 1 heading, so the first subsection at the start of a paper takes Level 2. Inside a thesis chapter your own numbering may therefore start a level lower than you expect — check your programme's template.

Example structure:

Literature Review

Theoretical Foundations Social Learning Theory Self-Efficacy Framework

Empirical Evidence Studies on Academic Performance Research on Student Engagement

Methodological Considerations Quantitative Approaches Qualitative Approaches

Identified Gaps and Future Directions

How to Write a Literature Review Introduction

The introduction sets up everything that follows. A strong literature review introduction should accomplish four things in roughly this order:

1. Hook and Context

Open with a statement that establishes why this topic matters. Avoid dictionary definitions ("According to Merriam-Webster...").

Example: "Full days worked at home accounted for about 28% of paid workdays among Americans aged 20–64 in mid-2023 — roughly four times the 2019 rate (Barrero et al., 2023)."

That opening works because the figure is checkable: it is stated in the abstract of a Journal of Economic Perspectives article with a DOI. Before you use any statistic as a hook, open the source and confirm the number, the population it describes and the year. An unsourced round number in a first sentence is the fastest way to lose a reader who knows the field.

2. Scope and Boundaries

Clarify what the review covers and what it excludes.

Example: "This review examines peer-reviewed research published between 2018 and 2024 on remote work's impact on employee productivity, excluding studies focused solely on freelance or gig economy workers."

3. Purpose Statement

State explicitly what the review aims to accomplish.

Example: "The purpose of this review is to synthesize current evidence on remote work productivity, identify methodological trends, and highlight gaps that warrant further investigation."

4. Organizational Preview

Tell readers how the review is structured.

Example: "The following sections examine productivity metrics, communication patterns, and work-life boundary management before discussing implications for organizational policy."

Real Literature Review Examples from Peer-Reviewed Sources

Examining published literature reviews helps you understand what good practice looks like. Here are five open-access examples across different fields:

Title	First author et al.	Journal/Source	Year	Open link	Why it's worth reading
Proposed solutions to anthropogenic climate change: A systematic literature review and a new way forward	Feigin et al. (Lueddeke is third author)	Heliyon 9(10), e20544	2023	PMC10585315 · 10.1016/j.heliyon.2023.e20544	Systematic method stated up front, thematic sections, explicit gap statement
Digital health for climate change mitigation and response: a scoping review	Rahimi-Ardabili, Magrabi & Coiera	JAMIA	2022	PMC9667157 · 10.1093/jamia/ocac134	Search strategy and inclusion/exclusion criteria documented in full
Rapid literature review: definition and methodology	Smela et al.	J Mark Access Health Policy 11(1), 2241234	2023	PMC10392303 · 10.1080/20016689.2023.2241234	A review about review methodology — useful for learning the process itself
Human-Centred Learning Analytics and AI in Education: a Systematic Literature Review	Alfredo et al. (preprint)	arXiv	2023	arXiv:2312.12751	Synthesises 108 papers against a stated analytical framework
Systematic Reviews in Educational Research: Methodology, Perspectives and Application	Newman & Gough, pp. 3–22	In Zawacki-Richter et al. (Eds.), Systematic Reviews in Educational Research, Springer VS	2020	10.1007/978-3-658-27602-7_1 (CC BY 4.0)	Clear explanation of aggregative vs. configurative synthesis

All five were checked against Crossref, PubMed Central or arXiv on 21 September 2026; all are free to read. Note the third row: a PubMed PMID (37533549) and a PMC ID (PMC10392303) are different identifiers for the same article, and mixing them up produces a link that goes nowhere. The fourth is a preprint, so label it as one if you cite it.

When reading these examples, pay attention to how the authors transition between sources, handle conflicting findings, and maintain a critical (not just descriptive) voice.

Reading a Finished Review as a Model

Rather than a mock-up, work from the real published reviews in the table above. Open one in your own field and read it twice: once for content, once for construction.

On the second pass, mark:

Where the introduction states the scope and the boundaries, and how many words that takes
How the body sections are grouped — by theme, by method, or by period
Every sentence that makes a claim about the literature as a whole, rather than about one study
How the authors handle two sources that disagree
Where the conclusion names a gap, and whether the preceding sections actually established it

Reviews published under an open licence are the most useful models here, because you can quote and annotate them freely. The Newman and Gough chapter in the table is CC BY 4.0; the three PubMed Central articles are open access.

Step-by-Step: How to Start Your Literature Review

Step 1: Define Your Research Question

Your review should answer a specific question. Too broad, and you'll drown in sources. Too narrow, and you won't find enough.

Too broad: "What is the impact of technology on education?" Too narrow: "How did tablet use affect third-grade maths scores at [one named school] in [one named year]?" Just right: "How do tablet-based interventions affect mathematical achievement in elementary education?"

(The middle one is bracketed on purpose: a question pinned to a single school in a single year is a study, not a body of literature to review.)

Step 2: Develop Your Search Strategy

Choose databases appropriate to your field:

Multidisciplinary: Google Scholar, Web of Science, Scopus
Health Sciences: PubMed, CINAHL, Cochrane Library
Education: ERIC, Education Research Complete
Psychology: PsycINFO, PsycARTICLES
Engineering/CS: IEEE Xplore, ACM Digital Library
Open metadata: OpenAlex and Semantic Scholar, which several research tools search on your behalf

Whichever you use, run the same search in at least two of them. Coverage differs, and a database your library does not subscribe to is not a database you have searched.

For the very first pass — the one where you are still working out whether your question has a literature — our free related-literature finder returns about ten real papers with a line each on what they contribute, with no account needed. It is one keyword search against one database, which is a starting point and not a search strategy; the rest of this step is still yours to do.

Create a list of search terms including synonyms and related concepts. Use Boolean operators (AND, OR, NOT) to combine terms effectively.

Step 3: Screen and Select Sources

Apply inclusion and exclusion criteria systematically:

Publication date range
Study type (empirical, theoretical, review)
Population or context
Language
Peer-reviewed status

Track your search process—where you searched, what terms you used, how many results you screened. This transparency strengthens your review's credibility.

Step 4: Read and Annotate

For each source, extract:

Key findings or arguments
Methodology and sample
Theoretical framework
Strengths and limitations
How it relates to other sources

Reference management tools like Zotero, Mendeley, or AI-powered research workspaces can help organize this information.

Step 5: Identify Themes and Organize

Group sources by theme rather than summarizing them one by one. Look for:

Points of consensus
Areas of debate
Methodological trends
Chronological developments
Geographic or population-specific patterns

Step 6: Write Synthetically, Not Sequentially

Both passages below are written from the same three real papers, cited in APA. Check them yourself: Bloom et al. (10.1093/qje/qju032), Gajendran & Harrison (10.1037/0021-9010.92.6.1524) and Barrero et al. (10.1257/jep.37.4.23).

Poor (source-by-source):

"Bloom et al. (2015) ran a working-from-home experiment at a Chinese travel agency. Gajendran and Harrison (2007) conducted a meta-analysis of telecommuting. Barrero et al. (2023) described how much work from home there is in the United States."

Better (synthesized):

"Evidence that remote work can raise output comes mainly from a small number of well-identified studies rather than from a broad base. In a randomised experiment at Ctrip, a 16,000-employee Chinese travel agency, home working produced a 13% performance increase, of which 9 points came from working more minutes per shift and 4 from more calls per minute (Bloom et al., 2015). An earlier meta-analysis of 46 studies in natural settings, covering 12,883 employees, reported 'small but mainly beneficial' effects on proximal outcomes such as perceived autonomy, along with beneficial effects on job satisfaction, performance and turnover intent that appeared 'at least partially mediated by perceived autonomy' (Gajendran & Harrison, 2007). The gap between one large single-site effect and a set of small average effects is the methodological question this review takes up — a question that matters more now that full days worked at home accounted for about 28% of paid workdays among Americans aged 20–64 as of mid-2023 (Barrero et al., 2023)."

Notice what the second version does: it makes a claim about the literature, then uses the sources as evidence for that claim, and it keeps each study's actual scope attached to its number. The 13% belongs to one call-centre experiment, not to remote work in general — losing that distinction is the most common way a synthesis paragraph becomes wrong.

Step 7: Revise for Critical Voice

Your review should evaluate, not just report. For each major claim, consider:

How strong is the evidence?
Are there methodological limitations?
Do findings generalize across contexts?
What alternative explanations exist?

The key point here is—do the sources agree or disagree with each other? As a whole, how strong an evidence do they provide?

How Long Should a Literature Review Be?

There is no published standard, and we are not going to invent one. Length is set by three things, in this order:

Your programme's or journal's own rules. A departmental handbook, a thesis regulation, or a journal's author guidelines will usually state a word count or a page range. That document is the authority, and it overrides any rule of thumb you read online — including this page.
The type of review. A systematic review has to report its search, screening and appraisal in enough detail to be reproducible, which makes it longer than a narrative review of the same field. See systematic vs. scoping vs. narrative review.
How much literature there actually is. A well-established field needs more space to cover than an emerging one.

If you have no stated limit, ask your supervisor for two or three recent, well-regarded examples from your own department and measure those. A local example beats a generic range.

The proportions in the outline above — roughly 10–15% introduction, 75–80% body, 10–15% conclusion — are a drafting aid for balancing a structure, not a requirement. A well-synthesised 3,000-word review is better than a padded 8,000-word summary.

Using AI Tools in Your Literature Review Process

AI-assisted tools can take some of the mechanical load off a review. What they can reasonably help with:

Source discovery: semantic search can surface papers that a keyword search misses because the authors used different vocabulary for the same concept.
Triage: a summary can help you decide which papers to read properly. It is not a substitute for reading them.
Citation management: extracting and formatting bibliographic data saves manual re-typing.

What they cannot do is judge whether a study's design supports its conclusion, or decide what your review argues. Those are the parts that make it a review rather than a list, and they stay with you.

Two practical rules: verify every reference an AI tool hands you against the DOI or the database record before you cite it, and check your institution's AI policy before you rely on any of this — disclosure requirements vary, and they are set locally.

References

Guides consulted for the advice on this page:

Purdue Online Writing Lab. Writing a literature review. https://owl.purdue.edu/owl/research_and_citation/conducting_research/writing_a_literature_review.html
Purdue Online Writing Lab. APA headings and seriation. https://owl.purdue.edu/owl/research_and_citation/apa_style/apa_formatting_and_style_guide/apa_headings_and_seriation.html — used for the APA heading formats above, because apastyle.apa.org blocks automated requests; the manual remains the authority.
Technological University of the Shannon Library. Literature review guide. https://tus.libguides.com/c.php?g=280076&p=1866569 — source of the source-count rules of thumb quoted in the FAQ.
University of North Carolina at Chapel Hill Writing Center. Literature reviews. https://writingcenter.unc.edu/tips-and-tools/literature-reviews/
University of Pittsburgh Library System. Literature reviews: Planning your review. https://pitt.libguides.com/c.php?g=1172750&p=8567945
PRISMA. (2021). PRISMA 2020 statement. https://www.prisma-statement.org/

Works cited as examples, each verified against its DOI record:

Barrero, J. M., Bloom, N., & Davis, S. J. (2023). The evolution of work from home. Journal of Economic Perspectives, 37(4), 23–49. https://doi.org/10.1257/jep.37.4.23
Bloom, N., Liang, J., Roberts, J., & Ying, Z. J. (2015). Does working from home work? Evidence from a Chinese experiment. The Quarterly Journal of Economics, 130(1), 165–218. https://doi.org/10.1093/qje/qju032
Gajendran, R. S., & Harrison, D. A. (2007). The good, the bad, and the unknown about telecommuting: Meta-analysis of psychological mediators and individual consequences. Journal of Applied Psychology, 92(6), 1524–1541. https://doi.org/10.1037/0021-9010.92.6.1524
Newman, M., & Gough, D. (2020). Systematic reviews in educational research: Methodology, perspectives and application. In O. Zawacki-Richter, M. Kerres, S. Bedenlier, M. Bond, & K. Buntins (Eds.), Systematic reviews in educational research (pp. 3–22). Springer VS. https://doi.org/10.1007/978-3-658-27602-7_1

Wonders searches OpenAlex and Semantic Scholar, keeps the papers you save on a project board, and exports your bibliography in APA, MLA, Chicago, Harvard, IEEE or Vancouver.