Outlines a strategy for the study of social interaction in the family that places particular emphasis on those variables that have proven useful or hold promise for the identification and understanding of factors that affect human social development. The heavy reliance on observational data and other main features of the approach are described, and an attempt is made to summarize some of the findings from this type of research that have added significantly to the understanding of social development within the family. Areas considered include the differentiation of distressed from nondistressed families; the process by which maladaptive social behaviors are learned; and the relationship between family structure, external stressors, and the vulnerability of families. The major research methods used in this approach are described, as well as areas of methodological improvement. A number of major gaps in substantive knowledge about social interaction within the family are indicated with respect to microsocial response structures and sex-typed behavior, support systems used by families, and the effects of stress on familial social interactional patterns.