Solving the most pressing problems of our time requires broad collaboration across political party lines. Yet, the United States is experiencing record levels of affective polarization (distrust of the opposing political party). In response to these trends, we developed and tested an asynchronous online educational program rooted in psychological principles called Perspectives. In Study 1, using a large longitudinal dataset (total N = 35,209), we examined Perspectives users’ scores on affective polarization and intellectual humility at pre- and post-intervention. Studies 2 and 3 were longitudinal randomized controlled trials with government finance officers (N = 341) and college students (N = 775), respectively, and examined the effects of Perspectives on affective polarization, intellectual humility, and conflict resolution skills. Across these studies, we found that Perspectives users experienced small to medium-sized decreases in affective polarization and small to medium-sized increases in intellectual humility. In Study 3, we found that Perspectives led to small yet significant improvements in conflict resolution skills. These findings suggest promise for a brief and scalable intervention to improve affective polarization, intellectual humility, and conflict management.