This research examined growth and co-occurrence of latent developmental patterns of classroom behavior problems among young, economically disadvantaged children. A nationally representative sample (N = 3,827) of children was assessed for overactive and underactive behavior problems through two years of prekindergarten, kindergarten and first grade. Latent growth mixture modeling revealed three distinct subpopulations of change in overactivity and two in underactivity. A parallel-process growth mixture model showed that well-adjusted patterns of overactivity and underactivity co-occurred in the majority of the sample, whereas co-occurrence of marginal overactivity and underactivity existed in approximately 7% of the sample. Results are discussed in light of theory and implications for practice.