Editorial The current number of Social Scientist is devoted to a discussion of certain theoretical trends which are being developed by Marxist academics in the United States. While these trends relate to Marxism in general, they are concerned specifically with the terrain pf Economics; they represent different perceptions of Marxism based on different reconstructions of Marxist economics. These perceptions may have their counterpart elsewhere as well, e.g. ip Europe, but they do in several important ways bear the imprint of their American origin. There are three distinct tendencies, or schools of thought, which emerge from the papers presented in this volume. The first is the so-called 'Social Structures of Accumulation' (SSA) school which in many ways is the American counterpart of the French 'Regulationist' school. According to the SSA school, capitalism is best understood as a system of power relationships which are exercised through specific institutional environments and within which the capitalist accumulation process is organised. It is these institutional environments which are called the social structures of accumulation. These structures do not remain immutable throughout the history of capitalism. On the contrary, the authors postulate a sort of cyclical phenomenon. Each particular set of SSA creates a setting for stable and profitable accumulation, and hence ushers in a period of extended growth. But growth itself, together with shocks of various kinds, undermines the ability of the particular SSA to sustain domestic capitalist power. This is reflected in declining rates of profit, which hamper accumulation, and usher in a period of crisis, marked by capitalists' efforts to reconstitute new social structures of accumulation. Within this general perspective, the authors belonging to this school have concentrated specifically on studying the social structures of accumulation of post-war US capitalism: their modus operand!, the manner in which they came under increasing stress, and the capitalists' efforts to reconstitute afresh a new set of institutions conducive to a further period of extended growth. Of particular interest is the authors' use of micro-economic modelling of processes and econometric testing of hypotheses, which in their view have a particular, albeit limited, role within their overall project. Notwithstanding certain obvious tensions within it, such as for instance the problematical relationship between the different levels of discourse—historical, theoretical and empirical—and the fuzziness surrounding the mode of transition from one set of SSA to another and the boundaries within which the attempts towards such a transition are made, the novelty of Social Scientist, Vol. 19, Nos. 1-2, January-February 1991