To progress beyond the idea that the value of interfirm collaboration is largely determined by the complementarity of the resources held by partners, we build a theoretical framework that explains under which conditions a set of resources or capabilities can be considered as complementary and resulting in superior value creation. Specifically, we argue that the tasks that an interfirm collaboration has to perform determine complementarities and that complementarities arise from similar and dissimilar resources alike. We capture this relationship in the concept of task resource complementarity. Further, we examine factors that impact on the relevance of this construct as a predictor of partner selection. Finally, we discuss which implications arise for a theory of the firm when tasks are explicitly incorporated into the conceptualization of resource complementarity.