This study looked at New Chance, a voluntary randomized trial of an intensive program for teenage mothers and their children that operated nationally between 1989 and 1992. The study examined the effects of maternal psychosocial well being, intensity of work and educational pursuits, home environment, and use of childcare on combined experimental and control group children's cognitive and behavioral development. Favorable home environment offered protection from poor cognitive development, as did mothers earning a high school credential. Risk factors for poor cognitive development were Hispanic ethnicity and long-term welfare receipt when the mother was a child, while maternal education was protective. Extended exposure to center-based childcare was protective for cognitive development for children under age one at intake. Mothers' depression and parenting stress were associated with higher maternal reported behavior problems, while minority status and earning a high school credential predicted fewer maternal reported behavior problems. Child sex (male) was the most important risk factor for poor teacher ratings. Use of childcare did not predict behavior, except that children over two years of age using the most center-based care were at an increased risk for poor maternal ratings. These findings suggest that programs should address parenting stress and continue to support and encourage education for teenage parents. (Contains 29 tables, 2 appendixes, 2 figures, and 107 references.) (MKA)