"In the 1970s Wallerstein embarked on the second phase of his intellectual journey and moved the locus of his work to a perspective he called “World‑systems Analysis“, based on two epistemic and methodological cornerstones. The first is that the determination of “a unit of analysis” is crucial. The modern social science presumed that the state boundaries constitute the boundaries of “societies.” Wallerstein asserted that this was a very misleading assumption that ignored dependencies and interdependencies in the world. Instead, he argued, the only plausible unit of analysis is a “world‑system”, whole interpolity system rather than single national society or delimited polities that implies closure. Secondly, all analyses have to be simultaneously historic and systemic, if they aspire to grapple seriously with the explanation of the reality and social changes."
- Oleg Komlik 
1. Via Geert Callens:
"Wallerstein first became interested in world affairs as a teenager in New York City, and was particularly interested in the anti-colonial movement in India at the time. He attended Columbia University, where he received a B.A. in 1951, an M.A. in 1954 and a Ph.D. degree in 1959, and subsequently taught until 1971, when he became professor of sociology at McGill University. As of 1976, he served as distinguished professor of sociology at Binghamton University (SUNY) until his retirement in 1999, and as head of the Fernand Braudel Center for the Study of Economies, Historical Systems and Civilizations until 2005. Wallerstein held several positions as visiting professor at universities worldwide, was awarded multiple honorary degrees, intermittently served as Directeur d’études associé at the École des Hautes Études en Sciences Sociales in Paris, and was president of the International Sociological Association between 1994 and 1998. During the 1990s, he chaired the Gulbenkian Commission on the Restructuring of the Social Sciences."
"Born in 1930, American sociologist Immanuel Maurice Wallerstein is best known for the development of world-systems theory—a comprehensive theoretical framework and methodology for the study of social change in the context of the global system of nations. World-systems theory has reshaped the sociology of development and has made Wallerstein one of the discipline's single most influential scholars.
Wallerstein's career began at Columbia University, where he served as an instructor (1958–1959), assistant professor (1959–1963), and associate professor of sociology (1963–1971). He then moved to Mcgill University in Montreal, serving as professor of sociology from 1971 to 1976. Wallerstein joined the State University of New York at Binghamton in 1976, where he was a distinguished professor of sociology until 1999, at which time he was named professor emeritus. In 2000 Yale University appointed Wallerstein as a senior research scholar. In addition, he has served as director of the Fernand Braudel Center for the Study of Economies, Historical Systems, and Civilizations since 1976, and has written and edited many books.
Wallerstein maintains that a new form of Western colonialism, neocolonialism, pursued mostly by the United States and various multinational corporations, has replaced old forms of colonial domination with indirect domination achieved through economic and political means. Examples of methods used to obtain indirect domination include the provision of economic aid, as well as monetary and trade policies.
In a slightly adapted version of the introductory essay to The Essential Wallerstein (New Press, 2000), posted on Yale University's Web site in 2006, Wallerstein explains: "World-systems analysis allowed me to range widely in terms of concrete issues, but always in such a way that the pieces might be fit together at the end of the exercise. It is not that world-systems analysis enabled me to 'discover the truth.' It is rather that it enabled me to make what I considered to be plausible interpretations of social reality in ways that I believe are more useful for all of us in making political and moral decisions. It is also that it enabled me to distinguish between what are long-lasting structures and those momentary expressions of reality that we so regularly reify into fashionable theories about what is novel, as for example, the enormous recent production concerning so-called 'globalization.'"
"Wallerstein’s intellectual influences include a wide range of scholars of various intellectual traditions. He has been influenced both by mainline political economists, such as Joseph Schumpeter (Schumpeter 1939) and Adam Smith (Smith 1999, first published in 1776), and by critical political economists, including Karl Marx (Marx 1967, first published in 1867–1894), Nikolai Kondratieff (Kondratieff 1992), Karl Polanyi (Polanyi 2001, first published in 1944), and Antonio Gramsci. Dependency theorists, including Raúl Prebisch and others, were important precursors to world-systems analysis, but perhaps more consequential was the influence of Pan-African thought on world-systems analysis, particularly the work of Frantz Fanon (Fanon 2004, first published in 1961) but also Walter Rodney (Rodney 1972), Amílcar Cabral, and Aimé Césaire. Annales School historians, particularly Fernand Braudel (Braudel 1981–1984), were significant influences in his work both on historical capitalism and on temporality. Wallerstein was also influenced by work in the hard sciences, particularly by concepts of uncertainty in the work of Ilya Prigogine (Prigogine 1997) and Ivar Ekeland (Ekeland 1988), but also was influenced by work in psychology—namely, Sigmund Freud. According to Wallerstein, his three greatest influences are Fanon, Braudel, and Prigogine."
From the Wikipedia:
"Wallerstein began as an expert on post-colonial African affairs, which he selected as the focus of his studies after attending international youth conferences in 1951 and 1952. His publications focused almost exclusively on this topic until the early 1970s, when he began to distinguish himself as a historian and theorist of the global capitalist economy on a macroscopic level. His early criticism of global capitalism and championship of "anti-systemic movements" made him an éminence grise with the anti-globalization movement within and outside of the academic community, along with Noam Chomsky (1928- ) and Pierre Bourdieu (1930-2002).
Wallerstein's most important work, The Modern World-System, appeared in four volumes between 1974 and 2011. In it, Wallerstein drew on several intellectual influences. From Karl Marx, Wallerstein took the underlying emphasis on economic factors and their dominance over ideological factors in global politics, and such ideas as the dichotomy between capital and labor, while criticizing the traditional Marxian view of world economic development through stages such as feudalism and capitalism, and while criticizing as well its account of the process of accumulation of capital, and of dialectics. From dependency theory, he took the key concepts of "core" and "periphery".
However, Wallerstein named Frantz Fanon (1925-1961), Fernand Braudel (1902-1985), and Ilya Prigogine (1917-2003) as the three individuals who exerted the greatest influence "in modifying my line of argument (as opposed to deepening a parallel line of argument)." In The Essential Wallerstein, he stated that: "Fanon represented for me the expression of the insistence by those disenfranchised by the modern world‑system that they have a voice, a vision, and a claim not merely to justice but to intellectual valuation."; that Braudel, for his description of the development and political implications of extensive networks of economic exchange in the European world between 1400 and 1800, "more than anyone else made me conscious of the central importance of the social construction of time and space and its impact on our analyses."; and that "Prigogine forced me to face the implications of a world in which certainties did not exist – but knowledge still did."
Wallerstein also stated that another major influence on his work was the "world revolution" of 1968. A member of the faculty of Columbia University at the time of the student protests, he participated in a faculty committee that attempted to resolve the dispute. He argued in several works that this revolution marked the end of "liberalism" as a viable ideology in the modern world system. He also argued that the end of the Cold War, rather than marking a triumph for liberalism, indicates that the current system has entered its 'end' phase: a period of crisis that will end only when it is replaced by another system. Wallerstein anticipated the growing importance of the North–South divide at a time when the main world conflict was the Cold War.
Wallerstein was often mocked for arguing since 1980 that the United States is a "hegemon in decline", but since the Iraq War this argument has become more widespread. During this time, Wallerstein also argued that the development of the capitalist world economy was detrimental to a large proportion of the world's population. Like Marx, Wallerstein predicted that capitalism will be replaced by a socialist economy, a view held in the 1970s, but reassessed in the 1980s. He concluded that the successor system(s) is unknowable."
- The Modern World-System.
"Wallerstein’s eye-opening and powerful World‑systems Analysis has transformed the way we understand history, capitalism, colonialism, liberalism, social sciences, and also the present turbulent times. It culminated in his four-volume masterpiece The Modern World-System (1974, 1980, 1989 and 2011) and three-volume collection of essays (The Capitalist World-Economy– 1979, The Politics of World-Economy– 1984, Geopolitics and Geoculture– 1991) in which Wallerstein generated a unique body of original and illuminating knowledge linking nations, political economies, ideologies, markets, classes, firms, households, labor, and identity groups."
* Book: The Essential Wallerstein. New Press, 2000.
"Immanuel Wallerstein is one of the most innovative social scientists of his generation. Past president of the International Sociological Association, he has had a major influence on the development of social thought throughout the world, and his books are translated into every major language. The Essential Wallerstein brings together for the first time the full range of his scholarship. This comprehensive collection of essays offers a unique overview of this seminal thinker’s work, showing the development of his thought: from his groundbreaking research on contemporary African politics and social change, to his study of the modern world-system, to his current essays on the new structures of knowledge emerging from the crisis of the capitalist world-economy. His singular focus on the way in which change in one part of the globe affects the whole is all the more relevant as the world grows increasingly interdependent. The Essential Wallerstein is an ideal introduction to the extensive body of work from a thinker who helped introduce globally sensitive thinking to the field of social science."
— Wallerstein, I. 2000. The Essential Wallerstein. The New Press (!!) — Wallerstein, I. 2004. World-systems Analysis: An Introduction. Duke University — Wallerstein, I. 1983/2011. Historical Capitalism with Capitalist Civilization. Verso — Wallerstein, I. 2006. European Universalism: The Rhetoric of Power. The New Press