This paper examines school productivity research--research regarding school effects on students, divided into two broad classes according to whether the dependent variable is (a) later life consequences or (b) immediate student outcomes. The discussion is organized in four sections. First, six major issues in the methodology of school productivity research are listed. This list provides some major reasons why school effects research may have been unsuccessful to date and suggests ways to better estimate the potential productivity of schools. Second, variables are introduced within the three domains of (1) school structure and organization, (2) social process, and (3) student outcomes. Specific aspects of these variables are examined to discover the role they play in the interplay between structure, process, and outcomes. Third, three directions for theory development which connect the organization, process, and outcome variables are outlined. A discussion of tradeoffs of school effects on students is presented. Trait-treatment interactions and individual differences are discussed. Parallel mechanisms of social control and individual motivation that are linked to the main organizational variables are detailed. The fourth section ties together the paper's conceptualization of school effects on student outcomes and suggests three broad kinds of research activity to make progress toward improving school productivity: (1) methodological studies to address some major technical issues in estimating school effects; (2) focused studies of specific causal connections between school organization properties, social processes, and student outcomes; and (3) basic research on processes of human motivation and environmental stimulus. (MM)