Fun activities are commonly sought and highly desired yet their affective side has received little scrutiny. The present research investigated two features of fun in two daily diary studies and one laboratory experiment. First, we examined the affective state associated with fun experiences. Second, we investigated the social context of fun, considering whether shared fun is more enjoyable than solitary fun. Findings from these studies indicated that fun is associated with both high-activation and low-activation positive affects, and that it is enhanced when experienced with others (especially friends). However, social fun was associated with increases in high-activation but not low-activation positive affect, suggesting that social interaction emphasizes energizing affective experiences. We also found that loneliness moderated the latter effects, such that lonely individuals received a weaker boost from shared compared to solitary fun. These results add to what is known about the impact of social contexts on affective experience.