Socializing, moving, working, and leisure form the foundation of human experience. We examined whether these foundational, ostensibly apolitical activities are nevertheless organized along political fault lines, revealing “lifestyle polarization.” In a sample of up to 1,373 young adults followed for up to 11,397 days, we quantified the association between political identity and 61 social, movement, work, and leisure behaviors collected from smartphone sensors and logs (i.e., GPS, microphone, calling, texting, unlocks, activity recognition) and ecological momentary assessments (i.e., querying activity level, activities, interaction partners, locations) at multiple temporal levels (i.e., daily, mornings, afternoon, evenings, nights, weekends, weekdays). We found that liberals and conservatives behave differently in everyday life. Behavioral differences between liberals and conservatives were small but robust, observed at most times of the day and week, and were most pronounced in the leisure domain. At the same time, these small behavioral differences were not accurately discerned by observers, who overestimated the extent to which liberals and conservatives within their community behave differently. Together, our results suggest that political identity has penetrated some of the most basic aspects of everyday life, but not to the degree that people think. We argue that lifestyle polarization has the potential to undermine individual wellbeing and societal cohesion.