A large body of research accumulated on the consequences that absolute team size (i.e., team headcount) entails for the performance of teams working on innovative tasks. However, there is a dearth of research on team size in relation to a team's assignments and objectives (i.e., relative team size). How this relative teamsize might influence innovation teams is therefore poorly understood. To stimulate theorizing on relative team size, we derive propositions from understaffing theory on how varying levels of relative team size affect teams with innovative tasks. We provide a more fine-grained analysis by differentiating between different dimensions of these teams' performance (i.e., team creativity, output quality, and team efficiency) and develop an input-mediator-output model. Implications of our theoretical considerations and avenues for future research are discussed.