Diversity in teams has been previously defined in terms of the nominal categories into which team members "fall". The core argument of this paper is that diversity is a subjective experience of social categories to which members "feel" they belong. These categories, or social identities, may become more or less salient in different contexts and at different times. We propose a model of diversity in teams that explains under what conditions these social identities become salient and how these social identities may influence appraisals of issues and events. These appraisals, in turn, can influence conflict and emotion. This dynamic view of diversity provides us with a better understanding of the "black box" -- the cognitive and affective processes that may help to explain behavior and subsequently team performance.