This guide is one part of a set of materials designed to support an ecological intervention system for families and their special needs children between birth and three. The system is constructed on four premises: (1) intervention is guided by the family; (2) parent-child interactions are the heart of early intervention; (3) family rituals, daily routines, and play reflect the patterns of family life and are the medium into which intervention is embedded; and (4) recorded ongoing observations and conversations between parents and interventionists are the basis for intervention decisions. The materials respond to the importance of multiple environmental influences on child and family life, the power and influence of interactions between parent and child, and the rights of families to fully guide the course and shape the content of the intervention program. The system is appropriate for early intervention, Head Start programs, day care centers, migrant programs, family resource centers, hospital personnel working with infants and premature babies, and others. The guide describes the research and literature foundation relating to each of the four premises and introduces the parts of the "Growing: Birth to Three" system. (Contains 60 references.) (JDD)