This study provides initial evidence for the criterion-related validity of tacit knowledge (TK) as an alternative measure for selecting psychology graduate students and adds insight to the construct of TK by evaluating its factor structure, assessing convergent relationships with other variables, and exploring alternative reasons for why TK predicts performance. TK provided incremental validity beyond GRE scores, undergraduate GPA, and 7 personality dimensions in predicting graduate school performance. Moreover, TK scores computed from experts at different universities yielded nearly identical criterion-related validity coefficients, thus strengthening the generalizability of the predictor. Although the results of the present study demonstrate convergent relationships between TK and conceptually related variables, factor analyses conducted on the TK measure did not support the subdimensions proposed by the authors of the scale. Limitations of the present study, issues involving revision of the TK measure, and recommendations for future research are discussed.