Islam is one of the fastest growing religions in America, with approximately 6 to 7 million Muslims living in America within the past decade. However, there has been little psychological research conducted focusing on the development of the Muslim American self. This inquiry addresses that gap by focusing on how familial religious affiliation during childhood and the everyday environmental activity systems of emerging adulthood impact religious practice and the construction of the religious self among Sunni-Muslim American emerging adults (N = 63, 18-29 years) via the development of diverse mediational strategies. Utilizing an applied cultural historical activity theory–based analysis, the authors found that participants’ religious development emerged as a diverse and dynamic process developing in relation to the interacting activity systems and sociorelational contexts of emerging adulthood.