Three conversations share this topic. Economists measure inequality and explain its trends: Piketty and Saez (2003) on US top incomes since 1913 and Chancel and Piketty (2021) on global inequality since 1820. Social epidemiologists ask whether unequal societies are less healthy: Kawachi et al. (1997), and Wilkinson and Pickett (2006; Pickett and Wilkinson, 2015). Sociologists and mobility researchers study consequences for opportunity and segregation (Corak, 2013; Reardon and Bischoff, 2011). This list covers works that have a DOI, so the field's older articles do not appear in it.
How the literature is organised
Measurement comes first in this field because the answer depends on the data. Deininger and Squire (1996) compiled a cross-country data set of Gini coefficients and quintile shares, wider and cleaner than what existed, and found no systematic link between growth and changes in aggregate inequality but a strong one between growth and falling poverty. Piketty and Saez (2003) used individual tax returns to construct US top income and wage shares from 1913 to 1998 and found a U-shape over the century, with "the working rich" replacing rentiers at the top. Chancel and Piketty (2021) use the World Inequality Database to estimate the world income distribution from 1820 to 2020. Bourguignon (1979) supplied the theory of decomposable measures.
The second conversation is about consequences. Kawachi et al. (1997), across 39 US states, found income inequality strongly correlated with lower social trust and group membership, and both in turn associated with mortality. Wilkinson and Pickett (2006) reviewed the evidence on inequality and population health, Lynch et al. (2000) set out three competing interpretations — individual income, psychosocial environment and neo-material conditions — and argued for the third, and Pickett and Wilkinson (2015) returned with a causal review. Corak (2013) sets out the Great Gatsby Curve linking inequality to lower intergenerational earnings mobility, and Reardon and Bischoff (2011) found a robust relationship between the growth in US income inequality from 1970 to 2000 and income segregation, working mainly through the large-scale spatial segregation of affluence.
Main debates
How much has top-end inequality risen? The series everyone cites comes from tax data, and other researchers have rebuilt it: Auten and Splinter (2024), in the Journal of Political Economy, measure long-term US trends from tax data and reach a different series from Piketty and Saez (2003). Read both before treating either as settled; their disagreement is about how unreported income, transfers and the unit of analysis are handled, not about the raw returns.
What drives the trend? Hémous and Olsen (2022) build a growth model in which the share of automation innovations rises endogenously with low-skill wages, raising the skill premium and lowering the labour share, and calibrate it to the US. Polacko (2021) argues the opposite emphasis, that inequality is not the inevitable outcome of structural forces but has largely been driven by political choices about union regulation, executive pay, the welfare state and tax progressivity. And does inequality hurt growth, help it or neither? Mdingi and Ho (2021) review eight theoretical channels and conclude the relationship can be negative, positive or inconclusive depending on which one dominates.
Where recent work is heading
Recent highly cited empirical work joins inequality to energy and the environment: energy poverty (Nguyen and Nasir, 2021; Dong, Dou and Jiang, 2022; Igawa and Managi, 2022; Hassan et al., 2022) and the environmental Kuznets curve (Wang, Yang and Li, 2023). The digital economy and the urban-rural gap in China (Peng and Dan, 2023) is another theme, and Junsen Zhang (2021) surveys inequality in China in the Journal of Economic Literature, documenting a negative correlation between income inequality and intergenerational mobility there too. Among the recent reviews, Tibber et al. (2022) cover adult mental health at subnational level, Jiekuan Zhang (2021) the effects of tourism, and Sebri and Dachraoui (2021) natural resources.
Most-cited foundational papers
Published before 2021 and ranked by how often later work cites them. Read the abstract of each and the full text of the three or four closest to your question. Citation count measures attention, not quality, so treat this as a map of what the field has argued about rather than a ranking of what is true.
Sean F. Reardon, Kendra Bischoff (2011). American Journal of Sociology.
Cited by 1,067doi:10.1086/657114
Most-cited papers since 2021
Primary studies and conceptual papers from 2021 onwards. A paper published in 2024 has had a few years to accumulate citations where the works in the section above have had decades, so compare these counts with each other rather than with the ones above.
Cited by 194Open accessdoi:10.1016/j.apenergy.2021.118076
Recent reviews and meta-analyses
The fastest way into a literature. A good review gives you the structure of the field, a reference list to mine and, in its limitations section, the gaps other researchers have already spotted.
How big the literature is, and where it is published
OpenAlex indexes 16,743 works whose title matches this topic. The chart shows how many were published each year from 2000 to 2025; the current year is left out because it is incomplete.
Show the numbers as a table
Year
Works
2000
145
2001
147
2002
149
2003
173
2004
198
2005
198
2006
211
2007
240
2008
288
2009
306
2010
332
2011
425
2012
559
2013
535
2014
659
2015
767
2016
790
2017
833
2018
812
2019
815
2020
844
2021
957
2022
858
2023
932
2024
987
2025
1,170
Journals behind the most-cited work
Counted across the 372 most-cited works on the topic, not across everything published. Browsing recent issues of the first two or three is a reliable way to find current work that has not yet been cited much.
Social Science & Medicine12 papers
BMJ10 papers
World Development10 papers
Environmental Science and Pollution Research9 papers
Resources Policy8 papers
American Journal of Sociology7 papers
American Sociological Review7 papers
Journal of Cleaner Production6 papers
Search strings to copy
Written for databases that accept Boolean operators (Scopus, Web of Science, ERIC, PubMed, EBSCO). Quotation marks keep a phrase together, an asterisk stands in for the end of a word, and OR groups go in brackets. British and American spellings are written out with OR rather than covered by a single-character wildcard, because those wildcards differ between databases: PubMed’s help page documents the asterisk only, and asks for at least four characters before it. Limit the search to title and abstract first; widen it only if you get too little. Our guide to starting a literature review covers how to record what you searched.
Causes and trends
("income inequality" OR "wage inequality" OR "top incomes") AND (trend* OR cause* OR (globalisation OR globalization) OR technolog* OR automation OR union*)
Inequality and health
("income inequality") AND (health OR mortality OR "life expectancy" OR "mental health") AND (multilevel OR "cross-national" OR review)
Inequality and growth or mobility
("income inequality") AND ("economic growth" OR "intergenerational mobility" OR "equality of opportunity" OR "social mobility")
Explore income inequality in Wonders →Opens Wonders on this question. Once you are signed in it becomes a project with suggested sub-topics and keywords you can edit before searching. The trial is 14 days.
Sub-topics to narrow into
A thesis-sized question usually sits inside one of these, combined with a population or a setting.
Measurement and data
Deininger and Squire (1996) assembled a cross-country data set of Gini coefficients and quintile shares; Bourguignon (1979) on decomposable measures.
Top incomes and long-run trends
Piketty and Saez (2003); Chancel and Piketty (2021).
Every paper above has a DOI, a part of the reference that is easy to leave out. Here is one of them, “Income Inequality in the United States, 1913-1998” (2003), in the two styles students ask about most:
APA 7th edition
Piketty, T., & Saez, E. (2003). Income inequality in the United States, 1913–1998. The Quarterly Journal of Economics, 118(1), 1–41. https://doi.org/10.1162/00335530360535135
MLA 9th edition
Piketty, T., and E. Saez. “Income Inequality in the United States, 1913–1998.” The Quarterly Journal of Economics, vol. 118, no. 1, 2003, pp. 1–41, https://doi.org/10.1162/00335530360535135.
Check the details against the article itself before you submit: databases, including the one behind this page, sometimes carry the online-first year rather than the volume year. Full rules and more examples are in our guides to APA, MLA, Chicago, Harvard, Vancouver and ABNT, with the rest in the citation guides. You can also format a reference from its DOI with our free citation tools.
Frequently asked questions
What is the Kuznets curve?
The Kuznets hypothesis is that inequality first rises and then falls as an economy develops, an inverted U. It is still used as a reference point rather than a settled law: Junsen Zhang (2021) reports that income inequality in China rose rapidly for three decades after 1978, then stabilised and slightly declined, which he reads as consistent with it. The idea travels by analogy into the environmental Kuznets curve, which relates pollution to income; Torras and Boyce (1998) reassess that curve with income distribution in the model, and Wang, Yang and Li (2023) ask whether income inequality reshapes it.
Does income inequality harm health?
Pickett and Wilkinson (2015) reviewed the evidence within an epidemiological causal framework and concluded that the body of evidence strongly suggests income inequality affects population health and wellbeing, with the criteria of temporality, biological plausibility, consistency and lack of alternative explanations well supported. They attribute most null findings to inequality being measured at an inappropriate scale, mediating variables included as controls, subjective health measures, or follow-up periods that are too short — so check those choices in any study you cite. Lynch et al. (2000) set out the competing readings and argue that interpretation must start from the structural causes of inequality rather than perceptions of relative position. At subnational level, Tibber et al. (2022) found that 55% of 42 studies supported the income inequality hypothesis for adult mental health, holding after controlling for absolute deprivation.
Which inequality measure should I use?
It depends on the question. The Gini coefficient is the default in cross-country data sets: Deininger and Squire (1996) built theirs from Gini coefficients and quintile income shares. Piketty and Saez (2003) instead report top income and wage shares built from individual tax returns, which is what lets them follow the top of the distribution back to 1913. Decomposable measures (Bourguignon, 1979) let you split inequality into within-group and between-group parts. Say which one you use and why, because the same country can look more or less unequal under each.
How this page was made
The lists come from OpenAlex, an open index of scholarly works whose data are published under a CC0 licence, queried on September 21, 2026 for works whose title matches "income inequality". Only works with a DOI are listed. Each one was checked against the publisher’s own record at Crossref or DataCite (title, year, first author, journal, volume and pages), and in three cases, where the publisher deposited no byline, against PubMed; anything OpenAlex or Crossref flags as retracted was left out, and an editor took out results that matched the words but not the subject. Citation counts are OpenAlex’s on that date and are usually lower than Google Scholar’s, which counts more kinds of document. Ranking by citations tells you what a field has relied on, not what is correct; several heavily cited papers on any topic are cited because later work disputes them. Books without a DOI are missing, which matters in fields where the founding text is a book.
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