A commonly used strategy for regulating emotions is known as expressive suppression (ES), in which a person attempts to conceal ongoing emotion-expressive behavior. ES has been frequently studied in adults and ample evidence indicates that it is linked to a host of negative outcomes, including depression and anxiety, suicide ideation, worse relationship and social functioning, cognitive impairment, and negative health outcomes. Relatively little is known about ES in children, despite the potential for ES to have lasting consequences on development (e.g., by contributing to a negative developmental cascade in which poor emotion regulation interferes with emerging competencies). The present study used a multi-method approach to investigate the emotional, physiological, and social behavioral correlates of both state and trait ES in middle childhood, a time when patterns of emotion regulation become more stable. Children ages 9 to 11 (n=117) reported their trait ES before coming into the lab, and then were randomly assigned to suppress or not suppress while watching a sad movie scene. Skin conductance was measured during and after the movie scene, and children gave multiple reports of their subjective emotions over the duration of the visit. After the movie scene, all children participated in tasks measuring prosocial behavior and empathy for others’ distress. Results indicated that trait suppression predicted skin conductance levels during the movie scene but did not predict emotions or social behavior. Group assignment did not affect outcomes. Exploratory analyses suggested that spontaneous ES of the control group during the movie scene predicted greater subjective feelings of sadness while suppressing. Additionally, exploratory mixed-effects models with child ratings of emotion nested within individuals suggested that trait sadness ES predicted changes in subjective sadness over the duration of the visit.