Organizations often rely on the match between job requirements and test content to justify test use. This practice has been questioned on the grounds that content validation has little relevance to criterion-related validation due to positive manifold among predictors. We analyze two large databases to assess the implications of test content for (a) test interchangeability and (b) criterion-related validity. Analyses of 15 knowledge tests administered (N = 80,394) as part of Project Talent demonstrate that test content is related to predictor interchangeability. Analyses of SAT and Advanced Placement test data compare correlations among predictors and criteria drawn from matched and unmatched content domains. We conclude that test-criterion content match is likely to result in stronger criterion-related validity.