This study intended to assess the effectiveness of a mutifocused indicated prevention program implemented in a community setting. The study was conducted on three (n = 3) preschool children with low levels of social–emotional competencies and high rates of externalizing problems. Using a multiple baseline design, observational data were gathered for four classroom behaviors: compliance to rules, frustration tolerance, prosocial behaviors, and cooperative play. The results suggest that the same intervention strategies which proved effective for clinically referred children are associated with decreased levels of externalizing problems for at-risk children targeted by this community-based intervention. Our study indicated that group interventions for at-risk children exhibit different effectiveness patterns compared with individualized interventions in clinical settings. Changes in observed behaviors in classroom settings are more likely to occur as a result of additive and interaction effects between different intervention strategies or as a result of enhancing age-related developmental processes.