This study employed a developmental-ecological approach to investigate the relationship across the school year between early problems in preschool classroom situations and a comprehensive set of readiness competencies for urban, low-income children. Study I identified three reliable and unique underlying classroom situational dimensions where behavior problems occurred: Structured Learning, Peer Interaction, and Teacher Interaction situations. Boys and younger children evidenced more problematic behavior across all situations. Study II investigated the relationship between early problems in the situations and readiness outcomes. Early situational difficulties uniquely and differentially predicted lower peer social and classroom learning outcomes. In combination, both the type of behavior problem (what) and the situational problem (where) explained greater variance in the prediction of readiness outcomes, contributing to a more comprehensive understanding of developmental trajectories.