Personal intelligence has been defined as the ability to reason about personality and personality-relevant information and to use that information to guide one's actions and more generally, one's life. We constructed an initial version of an ability-based measure to test whether personal intelligence can be measured and whether it exists as a unitary intelligence. In 3 studies (N = 241, 308, and 385), we administered this Test of Personal Intelligence (TOPI), composed of 4 sections, to undergraduates along with criterion measures. Results suggested that a personal intelligence can be measured, that it might exist as a unified area of mental abilities, and that it represents psychological qualities that have intriguing predictive aspects.