Research in personality psychology has remained predominantly correlational. For example, 3 decades of research demonstrate a robust cross-sectional relationship between extraversion and positive affect. A handful of studies, however, have examined this link experimentally, showing that extraversion boosts positive affect over short durations. If this is true, behaving in an extraverted manner should be a reliable method for increasing positive affect and, thus, suitable as a well-being-increasing practice. The current study instructed participants to engage in both extraverted and introverted behavior, each for 1 week. Participants increased in well-being when they were assigned to act extraverted and decreased in well-being when they were assigned to act introverted. These findings suggest that changing behavior associated with personality is possible and can impact well-being. More broadly, this study adds to a growing body of research on the potential of experimental methods in personality psychology. (PsycINFO Database Record (c) 2020 APA, all rights reserved).