This paper presents a structural-developmental model of social cognition and discusses the implications of this approach for social intervention research. This model of social development is concerned with social reasoning and judgment. The basic assumption of this model of social cognition is that the structure of social reasoning develops through an invariant sequence of 4 stages: (1) the "egocentric level," at which a child assumes that others feel or act as he does in similar situations, (2) the "subjective level," at which a child recognizes that others' thoughts, feelings, and intentions are distinct from his own, (3) the "self-reflective level," in which the child becomes aware that perspectives of self and others exist reciprocally, and (4) the "third person perspective level," at which a person, in a dyad, is aware of each other's subjectivity. These levels of perspective-taking are considered necessary, but not sufficient for parallel stages of interpersonal reasoning. Examples of this relationship, based on childhood friendship concepts, are provided. A hierarchical model of social cognition as it relates to interpersonal and moral stage theories is developed. Implications for social cognition intervention programs, derived from a study comparing the cognitive development, perspective-taking, and interpersonal and moral reasoning of 24 boys between the ages of 7 and 12 from special classes with that of a matched normal group of boys were discussed. (BRT)