Pro‐social behaviors have been associated with enhanced well‐being, but what psychological mechanisms explain this connection? Some theories suggest that beneficence—the sense of being able to give—inherently improves well‐being, whereas evidence from self‐determination theory (Weinstein & Ryan, 2010) shows that increases in well‐being are mediated by satisfaction of innate psychological needs for autonomy, competence, and relatedness. Here we simultaneously assess these two explanations. Study 1 (N = 335) used a cross‐sectional survey with an Internet sample to develop a measure to assess beneficence satisfaction. The next two cross‐sectional Internet‐sample studies tested mediators between pro‐social behavior and general well‐being (Study 2, N = 332) and situational peak moment well‐being (Study 3, N = 180). A fourth study (N = 85) used a diary method with university students to assess daily fluctuations in well‐being associated with needs and beneficence. It was shown across all studies that both the three psychological needs and beneficence satisfaction mediate the relations between pro‐social actions and well‐being, with all four factors emerging as independent predictors. Together, these studies underscore the role of autonomy, competence, and relatedness in explaining the well‐being benefits of benevolence, and they also point to the independent role of beneficence as a source of human wellness.