Adopting an interdisciplinary perspective, this article reports new evidence on the impact of age and experience on work unit performance. Two types of experience that increase with age are “general” and “firm-specific.” The focus here is on the influence of general human capital (which increases with time spent in the workforce) and firm-specific human capital (which increases with tenure with the current employer) on work unit performance. Although age–performance relationships have been investigated extensively in two research literatures, psychology and economics, neither addresses such relationships at the unit-within-organization level of analysis, concentrating instead on age–performance relationships at individual, organizational, or national levels. Using a unique data set comprised of large-sample, long-duration, multivariate studies of unit performance within firms this meta-analysis synthesizes partial effect sizes for the effects of age and tenure. A key finding is that tenure positively affects unit performance whereas age has no effect. Work unit leaders’ tenure but not age was found to positively affect unit performance. The lack of evidence of an age–performance relationship is consistent with psychological research at the individual level but contravenes economics research literature which, at all levels of analysis, generally reports negative relationships between age and performance. Neither the heterogeneity of tenure nor age was related to performance nor was there evidence of nonlinearities in relationships. Practical implications of the findings are discussed regarding ageism and employers’ use of gig or contract workers. Implications for future research and theory focus on interdisciplinary theory development and the scientific contribution of organizationally based research.