Previous studies have not longitudinally assessed whether religion is related to individuals’ movement into volunteering activities across the adult life course. Using four waves of panel data, I present evidence that religion is associated with individuals’ movement into religious institution and nonreligious institutional forms of volunteerism—volunteering for a religious congregation or other religious organization, and volunteering for a nonreligious institution, respectively. I consider the general religious mechanisms of changes in motivation to volunteer through enhanced religious beliefs and increased opportunities to volunteer through greater religious service attendance and involvement. Increased religious belief and attendance result in a greater probability that individuals engage in religious institution volunteerism. Religious institution volunteering increases the likelihood of movement into other formal volunteering over the adult life course. This analysis offers evidence that religious institutions are feeder systems, as increased involvement yields more opportunities for formal volunteerism over the adult life course, irrespective of underlying personality traits. Additionally, the findings suggest that religious mechanisms may operate differently across Christian religious traditions.