In this paper I focus on the role of generative models in explaining macrolevel dynamics. I argue that most macro-level dynamics of interest to sociologists are sufﬁciently complex to require the use of generative models, and that the under-formalized nature of sociological theory has hindered our efforts to properly explain many macro-level outcomes. To give substance to the general argument, I develop a model of network-based recruitment to a social movement which shows how the growth pattern of movements are likely to be inﬂuenced by the density of the social networks in which they are embedded.
I focus on the evolution of social movements and on the role of social networks in this process. I focus on this area because it is a substantively important area which is rich on micro-level ﬁndings and hypotheses but poor on generative models. I develop a model of network-based recruitment to a social movement and this model reveals results that could not easily have been anticipated without the aid of the formal model. To ensure that the abstract processes being analyzed correspond to real-world social processes, data on the evolution of a Swedish temperance movement is used to calibrate the theoretical model to reality.