Although a large body of research has examined the relative magnitude of validities of conscientiousness versus its facets, research has neglected another important issue -- the relative stability of conscientiousness factor versus facet validities across time. We addressed this issue using a sample of N = 173 employees across four years. The results indicated that global conscientiousness predicted performance across all four criterion measurement occasions and the magnitude of its validity did not change significantly across time. On the other hand, the conscientiousness facets were valid predictors of job performance only for certain time points and in some cases, the magnitude of their validities changed significantly across time. Implications for personnel selection research and practice are discussed.