This report discusses theories that contribute to an understanding of how schools and families interact. Shortcomings of these theories are examined, and the essential components of a new theoretical model are presented. Current theoretical perspectives on school-family relations focus on separate, shared, or sequential responsibilities of families and schools. Assumptions of these opposing theories are found in the perspectives and practices of teachers, parents, the teaching profession, and in patterns of family-school relationships. Four events in recent history help explain the movement from theories and practices that stress separation to those that stress partnership and overlap among family and school environments. Many schools now make their classrooms increasingly"family-like" to maximize learning and to improve student attitudes. Such overlap is a crucial component of a proposed theory which integrates useful strands from different theories and requires that research models include the history of, developmental considerations for, and change in family-school relationships. Such an integrated theoretical perspective suggests many new hypotheses for studies of relations and their effects, as well as family-school structures, their processes and effects. Changing theories and variations in school and family practices show that parent involvement is a variable that can be manipulated to increase school effectiveness and improve student success in school. (RH)