A conceptual model has recently been hypothesized in which parallel but correlated developmental pathways exist for attention deficit behaviors and conduct problems. An important component of this model suggests that attention deficit behaviors are related to later scholastic underachievement, whereas conduct problems are unrelated to scholastic underachievement except by their common correlation with attention deficit and intelligence. The present study replicated the general model using a cross-sectional sample of 325 children, and examined whether hypothesized dual pathways (behavioral and cognitive) better account for the relationship between attention deficit, intelligence, and later scholastic achievement. Results of the structural equation modeling analysis were consistent with the hypothesized dual pathway model and suggest that school behavior and select cognitive abilities serve as important mediators between attention deficit, intelligence, and later scholastic achievement. Implications of these results for understanding the developmental trajectory of children with attention deficit and general theoretical models of ADHD are discussed.