A model for the selection of individuals into institutions and their subsequent socialization is formulated which is defined in terms of qualitative rather than quantitative data; these data are hierarchical in character and are defined at several points in time. Variables defined for individuals and variables defined for institutions were distinguished. This partition of variables and, therefore their effect, implies a hierarchical model. This model allows the separation of the effects of policy-important institutional variables into structural (direct) and compositional (indirect) subcategories. The individual-level component of the model allows assessment of the distinct effect of each individual-level variable. On the basis of the institutional-level component of the model, two kinds of institutional effect may be assessed: those on the distributions of individual-level variables, i.e., on the kinds of persons acting in different institutions, and those directly on outcomes. Via the above decomposition of total effects in the model, both direct and indirect effects of institutional-level policy variables on outcome may be assessed: those mediated through the distribution of kinds of institutional actors and those directly affecting outcomes. (Author/RC)