The study found that youth with few behavioral problems throughout adolescence exhibited more indicators of thriving and less precocious behavior in late adolescence than those who had an early onset of behavioral problems. Even adolescents whose behavioral problems declined by age 19 tended to report fewer thriving indicators and more precocious behavior than those without a history of behavioral problems. These findings suggest that traditional broad-based youth-development strategies may be most effective if used for the prevention of behavioral problems that emerge during adolescence. These programs typically provide structured, supervised, and challenging opportunities to build on internal and external assets that promote positive behaviors and priorities; however, these strategies may be less effective at preventing behavioral problems that begin early in the child's life. This may require more intensive and targeted approaches in addition to the traditional broad-based strategies. Study participants were adolescents whose mothers had participated in a randomized intervention trial of a nurse home visitation program called the Elmira Nurse Family Partnership (Olds et al. 1997). The program was designed to improve mothers' pregnancy outcomes, children's health and developmental outcomes, and families' economic outcomes. Assessments were conducted at ages 3, 4, 15, and 19. Of the original sample of 400 children, 324 participated in the 15-year followup, and 310 participated in the 19-year followup. In addition, child protective services and school records were reviewed through age 15. Data from the 3-year- and 4-year assessments were collected through home observations and psychometric testing at the program office. Data from the 15-year assessment were collected through interviews with the study children and their mothers. Telephone interviews were conducted with the children when they were 19-years old. 4 tables and 68 references