Originally published in 1987, this book provides insights into what Robert Rapoport calls 'social inventions', in contrast to technical inventions. The author looks at ten projects in which behavioural science researchers collaborate with innovative action agencies in the children's mental health field. Each of the projects is described and analysed as a case study - revealing how the intervention took form, what contribution was expected from a collaborative relationship with a behavioural scientist, and what the actual experiences were in attempting to apply and disseminate knowledge arising from such a relationship. Though the book confronts the difficulties of action-research - both for practitioner and researcher - it emerges with an optimistic note and a wealth of practical and conceptual insights illuminating the way forward.