The Center for Comprehensive Health Practice in the East Harlem area of New York City operates an early intervention program called the Infant School to promote the healthy development of high-risk children from birth to 2 years of age, including those of mothers who had been users of cocaine and/or crack. The Infant School curriculum is designed to help mothers learn to enhance their children's cognitive, social, and emotional development through hands-on play activities. This study sought to assess the development of 23 children and to determine the effectiveness of early intervention program participation, through analysis of demographic factors, child's birth history, home environment factors, participation in program interventions, and the Bayley Scales of Infant Development. Most of the children were developing within normal parameters, and the scores' means were above average on the Mental Development Index and the Psychomotor Development Index. There were no significant correlations between the children's mental and motor scores and their attendance in the Infant School. However, the more the family had attended the Infant School, the higher the child scored on the Infant Behavior Record, which comprised three factors: test affect/extraversion, activity level, and task orientation. Possible explanations for these findings are discussed, and clinical implications are explored. Interview and observation forms are appended. (Contains 30 references.) (JDD)