New insights into what Robert Rapoport calls social inventions are examined in contrast to technical inventions. The author looks at ten projects in which behavioral science researchers collaborated with innovative action agencies in the children's mental health field. Each of the projects is described and analyzed as a case study, revealing how the new intervention took form, what contribution was expected from a collaborative relationship with a behavioral scientist, and what the actual experiences were in attempting to apply and disseminate knowledge arising from such a relationship. Children and youth with difficulties in coping with the stresses of contemporary society are not easy to study. Data on the personal and familial experiences of young people who may be victims of family violence, who are alienated from school, or in trouble with the law are difficult to obtain by conventional behavioral science techniques. In the projects described, behavioral scientists worked in family service agencies, schools, courts, and in the community. They became part of, yet independent of, the team efforts of creative service providers. They shared the goal of developing new ways to increase the competence of the young people themselves, rather than simply providing them with a palliative.