Early childhood development is a complex dynamic process that begins at birth and unfolds in a transactional manner as infants interact with their environment. Children are highly adaptive organisms with powerful homeostatic mechanisms; consequently, most high-risk infants do well. Environmental factors are powerful mediators in this process, and a supportive and responsive environment may alleviate many early developmental insults, while a deficient environment can exacerbate developmental weaknesses. Available data suggest that appropriately designed early intervention services can be effective in facilitating both child and family adaptation for a variety of target groups. However, many important questions remain unanswered. For example, although interventions have been shown to improve cognitive function, effects in other important areas such as social and emotional functioning and family coping have not been well studied. Information about the impact of family variables is also incomplete as is our knowledge about which services work best for which children and families. Finally, the influence of protective factors in the child and in the environment requires further exploration. The perinatologist can make several critical contributions to the comprehensive care of high risk infants beyond their medical management. He or she can play a pivotal role in identifying those neonates who need early intervention on the basis of their biologic vulnerability, their environmental risk factors, or both. Perinatologists are also in the best position to facilitate early entry into an appropriate service system and can be important collaborators in providing comprehensive services and long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)