This dissertation uses social movement theory to analyze the emergence, activities and development of subcultures and small groups. The manuscript is comprised of an Introduction followed by three journal articles and one book chapter.  The introduction discusses: 1) the concept of theoretical extension whereby a theory developed for one purpose is adapted to another; 2) it identifies the social movement theories used to analyze subcultures and small groups; 3) it describes the data used in the analyses included here. The data for this work derives from two distinct research projects conducted by the author between 2002 and 2012 and relies on multiple sources of qualitative data. Data collection techniques used include fieldwork, archival research, and secondary data. Paper I uses resource mobilization (RM) theory to analyze the origin, development, and function of White Power music in relation to the broader White Power Movement (WPM). The research identifies three roles played by White Power music: (1) recruit new adherents, (2) frame issues and ideology for the construction of collective identity, (3) obtain financial resources. Paper II gives an overview of the subculture of Freestyle BMX, discussing its origins and developments—both internationally as a wider subcultural phenomenon, and locally, through a three-year ethnographic case study of a subcultural BMX scene known as “Pro Town USA.” Paper III conceptualizes BMX as a social movement using RM theory to identify and explain three different forms of commercialization within this lifestyle sport in “Pro Town.” The work sheds light on the complex process of commercialization within lifestyle sports by identifying three distinct forms of commercialization: paraphernalia, movement, and mass market, and analyses different impacts that each had on the on the development of the local scene.  Findings reveal that lifestyle-sport insiders actively collaborate in each form of commercialization, especially movement commercialization which has the potential to build alternative lifestyle-sport institutions and resist adverse commercial influences. Paper IV refines the small group theory of collaborative circles by: (1) further clarifying its concepts and relationships, (2) integrating the concepts of flow and idioculture, and (3) introducing a more nuanced concept of resources from RM. The paper concludes by demonstrating that circle development was aided by specific locational, human, moral, and material resources as well as by complementary social-psychological characteristics of its members.