This study examines the effects of structured social activities on workplace collegiality and performance in a large white-collar firm with 100 geographically dispersed offices. In a randomized controlled trial, half of the offices received subsidies to organize biweekly social events over a three-month period—including picnics, movie nights, and team games. We find that the intervention strengthens collegiality, enhances workplace friendships, and improves office-level performance. We do not detect an impact on individual productivity, but turnover appears to have fallen in the short-run, meaning that employees stayed longer in the job. We explore possible mechanisms and identify a sense of gratitude and reciprocity toward the company as the most likely mechanism driving the effects.