Research shows that social engagement reduces the probability of cognitive decline in late life. The purpose of this study was to test whether religious attendance, a major source of social engagement for many older individuals, is associated with slower rates of cognitive decline among older Mexican Americans. Using four waves of data collected from a sample of 3,050 older Mexican-origin individuals, we estimated a series of linear growth curve models to assess the effects of religious attendance on cognitive functioning trajectories. We used the Mini-Mental State Examination to measure cognitive functioning. Our central finding is that religious attendance is associated with slower rates of cognitive decline among older Mexican Americans. Specifically, respondents who attend church monthly, weekly, and more than weekly tend to exhibit slower rates of cognitive decline than those who do not attend church.