This paper situates Bogdanov in the context of social theory generally and socialist theory in particular. It outlines briefly the principal characteristics of his mature system, and assesses the strengths and weaknesses of his approach to the fundamental problems of social thought. The paper devotes particular attention to the problem of just how systems develop from less complex to more complex forms of organization, and evaluates Bogdanov’s solution to this problem against the background of populist, social democratic, and Leninist alternatives.