Having close social connections powerfully predicts well-being and longevity (Holt-Lunstad, Smith, & Layton, 2010). Our study examined whether taking a 6-week mindfulness meditation training would lead to gains in perceived social connection from pre to post training, compared to an active-control wellness training group. We also examined possible cognitive and emotional mechanisms of this hypothesized effect. Using a randomized control trial design of these two trainings (N = 94), we found that both groups exhibited gains in social connection from pre to post-training. When we examined the role of trait mindfulness, however, we found that individuals who exhibited gains in their trait mindfulness levels across training also exhibited greater gains in their perceived social connection. This association was mediated, or explained by boosts in the cognitive ability of decentering (i.e., the ability to distinguish one’s awareness of experience and the perceived self-focus of that experience). We also found that gains in social connection predicted boosts in positive emotions. In sum, social connection, which has been linked to vital health and well-being outcomes, may be boosted by gains in trait mindfulness and decentering, and subsequently lead to boosts in positive emotions.