Direct social ties bolster mental health; do ambient features of local communities also play a role? This work takes advantage of university students’ assignment to different local networks—or “social microclimates”—to probe this question. We quantify the collective impact of individual, social network, and microclimate factors in the well-being of a cohort of first-year college students. Students who belonged to emotionally stable and tight-knit microclimates reported reduced psychological distress, even when controlling for factors such as personality and personal social ties. Although rarely discussed or acknowledged in the policies that create them, social microclimates are consequential to mental health, especially during life transitions.