Work conducted by the Clinical Infant Development Program (CIDP) of the National Institute of Mental Health, involving 47 multirisk families and their infants over a period of several years, is described. Part I contains four detailed case studies by Delise Williams, Euthymia Hibbs, Serena Wieder and others, providing data for comprehensive clinical preventive approaches for infants and their families. Several analytic chapters are also included: "Staffing, Process, and Structure of the Clinical Infant Development Program" (Serena Wieder and Stanley Greenspan); "The Infant Center: A Developmentally Based Environment to Support Difficult Lives" (Serena Wieder and Patricia Findikoglu); and "Reaching the Unreachable: Measuring Change in Relation to Intervention" (Serena Wieder). Part II, titled "Models for Clinical Programs," includes: "Antecedent Psychosocial Factors in Mothers in Multirisk Families: Life Histories of the 47 Participants in the Clinical Infant Development Program" (Serena Wieder et al.); "A Model for Comprehensive Preventive Intervention Services for Infants, Young Children, and Their Families" (Stanley Greenspan); "Dimensions and Levels of the Therapeutic Process" (Stanley Greenspan and Serena Wieder); "A Developmental Diagnostic Approach for Infants, Young Children and Their Families" (Stanley Greenspan, et al.); and "Conclusions: Theoretical Perspectives on Research Regarding Psychopathology and Preventive Intervention in Infancy" (Stanley Greenspan). Appendices focus on a model of cost-effectiveness analysis of services, and the clinical entry ratings used by the CIDP. (JDD)