At some point, hiring managers in all organizations face the decision of whether to fill open positions with internal candidates (e.g., through promotions) or to hire external candidates (e.g., from competitors or new entrants into the labor market). Despite this ubiquitous choice, surprisingly little research has compared the effectiveness of internal and external selection or has identified situations in which 1 approach may be better than the other. The authors use theory on human capital resources to predict differences between internal and external hires on manager- and unit-level outcomes. Analysis of data from a quick-service retail organization (N = 3,697) suggested that internally hired managers demonstrated higher levels of individual job performance and commanded lower starting salaries than externally hired managers. At the unit-level, operations led by internal hires demonstrated higher performance on organization-specific criteria (i.e., service performance), whereas no internal-external differences were found on more general criteria (i.e., financial performance). They also found some evidence that differences in unit service performance decreased over time (but did not diminish completely) as external hires improved at a slightly faster rate than internal hires. Overall, these findings underscore the complexity of the recurring "build or buy" decision. The results also suggest that internal hires generally outperform external hires, both individually and collectively, and they do so for less money. (PsycINFO Database Record