Much of Elster's writing is characterized by attempts to use analytical theories, especially rational choice theory, as a springboard for philosophical and ethical analysis, with numerous examples from literature and history. "Elster has made important contributions to several fields," Daniel Little wrote in a review essay. "The breadth and depth of his writings are striking in a time of high specialisation; he is read and discussed by political scientists, economists and philosophers. His work is difficult to summarise in a slogan, but ... it is generally informed by a broad and deep acquaintance with relevant literature in economics, political science, history, philosophy, and psychology."
A student of the philosophy of social science (a topic he investigated through case studies in Explaining Technical Change), Elster strongly argued that social scientific explanations had to be built on top of methodological individualism (the belief that only individuals, not larger entities like "organizations" or "societies", can actually do things) and microfoundations (explaining big societal changes in terms of individual actions). He criticized Marxists and other social scientists for believing in functionalism (the belief that institutions exist because of their effect on society) and instead tried to give Marxism a foundation in game theory (the economic notion that people based on the expected benefits and the choices others are likely to make).
Elster wrote numerous books attempting to use rational choice theory for a wide variety of social explanations. "Rational choice theory is far more than a technical tool for explaining behaviour," he once wrote. "It is also, and very importantly, a way of coming to grips with ourselves - not only what we should do, but even what we should be." He attempted to apply it to topics as varied as politics (Political Psychology), bias and constrained preferences (Sour Grapes), emotions (Alchemies of the Mind), self-restraint (Ulysses and the Sirens), Marxism (Making Sense of Marx) and more.
In doing so, he elucidated many issues with simplistic notions of rational choice: endogenous preference formation (certain actions today can change preferences tomorrow, so how does one decide which preferences one prefers?), hysteresis (people express different preferences when the same question is asked different ways), imperfect rationality (weakness of the will, emotion, impulsiveness, habit, self-deception) and our adjustments for it, and time preferences, among others.
As time went on Elster began to sour on rational choice. A 1991 review in the London Review of Books noted "Elster has lost his bearings, or at least his faith. [His latest books], he says, 'reflects an increasing disillusion with the power of reason'." His magisterial 500-page book Explaining Social Behavior includes something of a recantation:
I now believe that rational-choice theory has less explanatory power than I used to think. Do real people act on the calculations that make up many pages of mathematical appendixes in leading journals? I do not think so. ... There is no general nonintentional mechanism that can simulate or mimic rationality. ... At the same time, the empirical support ... tends to be quite weak. This is of course a sweeping statement. ... let me simply point out the high level of disagreement among competent scholars ... fundamental, persistent disagreements among 'schools.' We never observe the kind of many-decimal-points precision that would put controversy to rest.
The book discusses both rational behavior, but also irrational behavior, which Elster says is "widespread and frequent [but] not inevitable ... we want to be rational". His most recent work, Le désintéressement (part of a projected three-volume Traité critique de l’homme économique) explores the ramifications of these insights for the possibility of disinterested action.
Leibniz et la formation de l'esprit capitaliste (Paris, 1975) ISBN 2-7007-0018-X
Leibniz and the development of economic rationality (Oslo, 1975)
Logic and Society (New York, 1978)
Ulysses and the Sirens (Cambridge, 1979)
Sour Grapes: Studies in the Subversion of Rationality (Cambridge, 1983)
Explaining Technical Change : a Case Study in the Philosophy of Science (Oslo, 1983)
Chapter on Jon Elster by Daniel Little in New Horizons in Economic Thought: Appraisals of Leading Economists, edited by Warren Samuels (Edward Elgar Publishing, 1992) ISBN 1-85278-379-6. Also available as download 
Elster, Jon (1993). "Some unresolved problems in the theory of rational behaviour". Acta Sociologica36 (3): 179–189 [p. 179]. doi:10.1177/000169939303600303.
Hollis, Martin, Why Elster is stuck and needs to recover his faith, London Review of Books, 13 January 1991
Explaining Social Behaviour, pp. 5, 25ff
Explaining Social Behaviour, p. 232
Review of Le désintéressement, by Gloria Origgi, The Possibility of Disinterested Action, The Berlin Review of Books, 8 January 2010.