Wallerstein is best described as a world-social theorist, a theorist and analyst of a "world-society" which is within a World-System. His work is therefore of tremendous cosmopolitan use and of the absolute highest priority for anyone interested in themes of inequality and oppression of the downtrodden.
However, I recommend more recent literature from Wallerstein, such as World-Systems Analysis: An Introduction and The Essential Wallerstein, as well as a whole collection of other more concise and more valuable works in which this man really establishes his true contributions to social theory.
While the prevailing misconception in academia is that "Marxist" theory perished with the Soviet Union, and these essays were published in this book in 1979 by a man commonly described as a Marxist theorist, Wallerstein's contributions to social theory are possibly the greatest available now in the economic turmoil of the Twenty-First Century, and the only real key to the development of a rational perspective on global society. With progressivism in a constant state of failure since 1945, and global inequality literally multiplied by 75 times during that period of so-called progressive and liberal global governance, we have overwhelming evidence that a Capitalist World-Economy has set the parameters of the international scene, and has promised only the "progress" of evil. Although Wallerstein could be pulled under the definition of a progressive himself, the radical spirit with which he treats the conflicted ideas of progressivism and the ways of reaction is an inspiration for the re-evaluation of the international scene and eventual visualisation of the way to gain a substantively rational world. If man seeks to escape the ever worsening abyss of poverty and unnecessary death at last, it is in Wallerstein's social theory that we need to look to develop the necessary rational points of view.