We implemented a five-week family program called "Family Quest" where parents and children ages 9 to 13 played Quest Atlantis, a multiuser 3D educational computer game, at a local after-school club for 90-minute sessions. We used activity theory as a conceptual and an analytical framework to study the nature of intergenerational play, the collaborative activity between parents and children in the context of role-playing virtual game environment, and the opportunities and challenges of bringing parents and children together around an educational video game. Our analyses of five parent-child dyads revealed that the nature of intergenerational play is different for different parent-child dyads, but has positive outcomes. Implications of the study for supporting family learning and bonding through video games are discussed. (Contains 3 figures, 2 tables and 1 footnote.)