Although the word has been reduced in public usage to an ideological level, serious scholars are still trying to come up with a useful concept of imperialism. In this survey, first published in German in 1977, historian Mommsen lays out the terrain by reviewing various theories of imperialism by types. In a very concise presentation, Mommsen looks at the first ""political"" interpretation of imperialism, put forward in the post-WW I period by Heinrich Friedjung, seeing it as a manifestation of national rivalry and the desire to expand dominion. This is counterpoised to the earlier and very influential economic theory of English journalist J. A. Hobson, which saw the cause of imperialism in surplus capital and the need for external markets, combined with a political ideology of nationalism. The opening discussion is rounded out with the theory of Joseph Schumpeter that imperialism has ""atavistic"" roots, being the product of the pre-capitalist mentality of European aristocracy before the Great War. Mommsen then proceeds through theories which develop one or more of these themes, including the Hobson-inspired ideas of Lenin, the power-politics theories of William Langer, and the Schumpeterian views of Hannah Arendt. But added on to these basic types are some newer innovations, like theories that emphasize the importance of local elites that pressure the metropolitan government toward imperialist policies, or the theories of ""informal imperialism"" which stress both overt and covert imperialism (i.e., direct political rule and indirect economic control). Other theories develop the economic ideas in different ways, as in theories of underdevelopment or of monopoly capitalism. The upshot of Mommsen's survey, like many basically typological studies, is simply to emphasize the multilayered phenomenon of imperialism without settling on one or another of the definitions or theories. But as a review of the literature, this is an excellent handbook.