The study found that although 60.6 percent of the 4-year-olds exhibited borderline or clinical-level externalizing behaviors during at least one wave of the study, the majority of the children followed a normal or improving course of behavior over time, as reported by parents and caregivers. Weighted results show that 61.4 percent of the children followed a consistently low problem trajectory, remaining within the normal range on average over 6 years. Only 11.6 percent of the children followed a persistently high problem trajectory. On average, the children in the persistently high problem group scored in the clinical range at age 4 and continued on a high, clinical-level trajectory through elementary school; 4.4 percent began with moderate problem behaviors and increased into the clinical level of externalizing behaviors over the 6 years. The identification of children most at risk of behavioral problems in this high-risk population may help practitioners provide problem-focused interventions in the early years that will increase the chance for successful transition into elementary school. This study used data from the National Study of Child and Adolescent Well-being (NSCAW). The sample included 246 4-year-olds who remained home after investigation. Latent class growth analysis was used to estimate the number, size, and shape of subgroups of preschoolers following distinct behavioral pathways. Early predictors of membership in the resulting groups were then examined. 6 tables, 1 figure, and 59 references