Stable social relationships are conducive to well-being. However, similar effects are not reported consistently for daily social interactions in affecting episodic (experiential) subjective well-being (ESWB). The present investigation suggests that the choice of being in a social context plays an important moderating role, such that social interactions increase ESWB only if taken place by one's choice. Moreover, it is argued that choice matters more in a social context than in an alone context because experiences with others are amplified. These ideas were tested and supported in two studies: An experiment that manipulated social context and choice status, and a 10-day experience-sampling study, which explored these variables in real-life settings. Results showed that being with others by one’s choice had the strongest positive association with ESWB, sense of meaning, and control, whereas being with others not by one’s choice—the strongest negative association with ESWB. Effects of being alone on ESWB also varied by choice status, but to a lesser extent. The findings offer theoretical and practical insights into the effects of the social environment on well-being.