We compared long-term growth patterns in teachers’ and mothers’ ratings of Overt Aggression, Covert Aggression, Oppositional Defiance, Impulsivity/inattention, and Emotion Dysregulation across developmental periods spanning kindergarten through grade 8 (ages 5 to 13 years). We also determined whether salient background characteristics and measures of child temperament and parenting risk differentially predicted growth in discrete categories of child externalizing symptoms across development. Participants were 549 kindergarten-age children (51% male; 83% European American; 17% African American) whose problem behaviors were rated by teachers and parents each successive year of development through 8th grade. Latent growth curve analyses were performed for each component scale, contrasting with an overall index of externalizing, in a piecewise fashion encompassing two periods of development: K-1and grades 1–8. Our findings showed that there were meaningful differences and similarities between informants in their levels of concern about specific forms of externalizing problems, patterns of change in problem behavior reports across development, and in the extent to which their ratings of specific problems were associated with distal and proximal covariates. Thus, these data provided novel information about issues that have received scant empirical attention and have important implications for understanding the development and prevention of children’s long-term externalizing problems.