Abundant research supports a cognitive foundation to teamwork. Team cognition describes the mental states that enable team members to anticipate and to coordinate. Having been examined in hundreds of studies conducted in board rooms, cockpits, nuclear power plants, and locker rooms, to name a few, we turn to the question of moderators: Under which conditions is team cognition more and less strongly related to team performance? Random effects meta-analytic moderator analysis of 107 independent studies (N = 7,778) reveals meaningful variation in effect sizes conditioned on team composition and boundary factors. The overall effect of team cognition on performance is ρ = .35, though examining this effect by these moderators finds the effect can meaningfully vary between ρ = .22 and ρ = .42. This meta-analysis advances team effectiveness theory by moving past the question of “what is important?” to explore the question of “when and why is it important?” Results indicate team cognition is most strongly related to performance for teams with social category heterogeneity (ρ = .42), high external interdependence (ρ = .41), as well as low authority differentiation (ρ = .35), temporal dispersion (ρ = .36), and geographic dispersion (ρ = .35). Functional homogeneity and temporal stability (compositional factors) were not meaningful moderators of this relationship. The key takeaway of these findings is that team cognition matters most for team performance when—either by virtue of composition, leadership, structure, or technology—there are few substitute enabling conditions to otherwise promote performance.