Using a grounded theory method, the authors explore the phenomenon of adult play guilt, or the negative emotions associated with the perception of being unproductive while engaging in play. They interviewed twenty-four emerging adult undergraduate students about feeling guilty when contemplating or engaging in play. The authors found that participants often experienced guilt as an internal voice urging them to do something other than playing, especially when their academic workloads were heavy. Guilt struck at different times (before, during, and after play) and could prevent play, or cut it short, or reduce its pleasure. Participants felt less guilt when they conceptualized their play as productive, or beneficial, or as a reward for hard work. The authors conclude with suggestions to improve the understanding of adult play and its import for healthy and fulfilling lives.