This dissertation seeks to explore how, and under what circumstances, living as a religious minority or majority at the local level shapes the social identities, outgroup perceptions, and religious commitments of religiously active evangelical Protestants and Latter-Day Saints in the contemporary United States. Qualitative interviews were conducted with both groups in two very different local religious ecological contexts: Knoxville, Tennessee (and neighboring Oak Ridge), where Protestants represent a local religious majority and Latter-Day Saints represent a small local minority; and Utah County, Utah, where Latter-Day Saints represent a strong local majority and evangelical Protestants represent a small local minority.The dissertation argues that local religious minority and majority contexts have diverse effects on religious adherents. Local religious minority contexts, for example, tend to increase opportunities for contact and engagement with local majority outgroups and decrease opportunities, or increase the associated costs, of some specific within-tradition forms of religious participation. Local religious majority contexts can sometimes, in contrast, "normalize" religious commitments and foster more open religious "conversational rules," or even favorable sociolinguistic subcultures. Building off of previous theoretical frameworks, various pathways through which "engagement" with religious or secular others can reinforce religious worldview commitments are identified. The motivations of respondents to engage with religious others and their frames for understanding religious difference are also explored.Differences in the experiences of minority and majority context based on religious tradition are also identified. Variation in the cultures and organizational structures of the two groups account, in part, for their different experiences in the two contexts. Religious traditions place different types of demands on members. They also create resources to help members fulfill these demands that can be unequally distributed. Differences in the forms and structures of religious congregations also shape religious minority and majority experiences. In areas with strong Mormon-majorities, for example, ward boundaries at times shrink to the point that the distinction between "neighborhood" and "congregation" is blurred. In short, there is no universal religious "majority" or "minority" experience. These experiences are shaped, in part, by the specific cultures and organizational structures of religious traditions.Finally, this dissertation seeks to explore, through rich description, the encounter between evangelical Protestants and Latter-Day Saints within the contemporary United States. How these two groups understand the differences and commonalities between their respective movements are explored in detail, as well as the experiences of each group living on the other's "turf."