Understanding the factors that affect participation in online games will help educational game designers develop games that maximize participation. This study investigated whether introversion or extroversion, player motivation, and gender affected participation in online games. Participants (n = 400) completed a 50-item questionnaire about introversion or extroversion, player motivation, and time spent playing games. A three-way analysis of variance was used to explore the effects of personality, player motivation, and gender on participation. Introverts spent 6.7 more hours playing games than extroverts, and a significant interaction effect was found between personality and gender. The implications of these findings are presented.