AbstractSocial platforms facilitate the daily interactions of billions of people globally. Prior research generally concludes that social platforms negatively affect people's welfare. This research reopens this debate by using a robust methodology to examine the time series effects of social platform use on users' subjective well‐being, psychological well‐being, physical health, and financial security. We report a 6‐month longitudinal study of 1029 adults. Participants' daily time using social platforms on their mobile device was unobtrusively tracked and their well‐being was measured every 2 weeks. The findings suggest a small, positive effect of time spent using social platforms on both subjective well‐being and psychological well‐being (but no significant effects on physical health or financial security). Further, it is time spent using social platforms that facilitate interactions with intimate/close ties, that is correlated with positive subjective and psychological well‐being.