The 2 goals of this study were to develop and validate a performance measure of personal wisdom (PW) and to examine age differences. On the basis of the Berlin wisdom paradigm and growth theories of personality, 5 criteria of PW were developed. A sample of 83 younger adults (ages 20–40) and 78 older adults (ages 60–80) thought aloud about a PW task. Transcribed answers were rated. Validity was established with regard to indicators of personality growth, subjective well-being, intelligence, critical life events, and general wisdom. As expected, no age differences were obtained on the basic criteria, and negative age differences were found on the metacriteria indexing PW. Fluid intelligence and openness to new experience partially mediated these differences. It is argued that on average and for current cohorts age-related changes in psychological functioning may act as hindrances on the road to PW.