Using longitudinal data on 585 youths (48% female; 17% African American, 2% other ethnic minority), the authors examined the development of social response evaluation and decision (RED) across childhood (Study 1; kindergarten through Grade 3) and adolescence (Study 2; Grades 8 and 11). Participants completed hypothetical-vignette-based RED assessments, and their antisocial behaviors were measured by multiple raters. Structural equation modeling and linear growth analyses indicated that children differentiate alternative responses by Grade 3, but these RED responses were not consistently related to antisocial behavior. Adolescent analyses provided support for a model of multiple evaluative domains of RED and showed strong relations between aggressive response evaluations, nonaggressive response evaluations, and antisocial behavior. Findings indicate that RED becomes more differential (or specific to response style) and is increasingly related to youths' antisocial conduct across development. (Contains 1 footnote, 4 tables, and 2 figures.)