This dissertation examines the construction and maintenance of religious identity and solidarity among members of the Church of Jesus Christ of Latter-day Saints (the LDS or Mormon church) in the United States. Specifically, this study explores how the constituent elements of Mormon identity and solidarity are fashioned as Mormons negotiate the demands of a larger society, and react to pressures created by the growth and geographic dispersion of Mormonism. The dissertation also describes the nature and extent of these constructions by contrasting Mormon life in Utah-where Mormons enjoy overwhelming numerical and cultural dominance-with places where Mormons are a tiny minority in pluralistic milieux. The study is a comparative congregation study contrasting the construction of religious identity and solidarity in two Mormon parishes, or "wards." The first ward is in a locus of Mormon culture: a suburb of Salt Lake City that is over 90% Mormon. The second ward is in suburban New Jersey (49th among states in per capita Mormons), where less than .3% of the population is LDS. Contrasting these disparate wards reveals the processes of Mormon identity and solidarity construction in the nation's most and least Mormon places. Data for the study include ethnographic interviews of ward members, multiple discussions with key informants from each location, secondary analyses of ward membership data, and almost three years of extensive participant observation divided between the wards. The study finds that the vitality of the New Jersey congregation is ensured by a strong emphasis on self-control, asceticism, and separation from the larger society. In contrast, vitality in the Utah ward is enhanced through pervasive kinship ties, a shared cultural heritage, and residence in a common homeland. The comparison of these two disparate congregations is used to theorize about the construction and maintenance of religious identity and solidarity in the United States. This work also contributes to a growing literature on the sociology of Mormonism, and attempts to address several major issues in the sociology of United States religion.