Benefits accrue to individuals from their social relationships, and these benefits may serve as resources. A study focused on the structure and implications of voluntary association, both between and within U.S. secondary schools. It studied both the qualities of social relationships in high schools and the schools' organizational characteristics. The study explored the advantages and disadvantages of internal and external choice, drawing on data from two projects that examined social capital in 10 high schools, using qualitative methods. An example of external choice would be choice between schools. An example of internal choice would be choice among small learning communities in high schools organized into schools-within-schools. A major benefit of choice is the commitment that students, parents, and teachers bring to the schools or subunits whose themes, values, and norms are aligned with their own. Such commitment typically leads to productive relationships among school members. That is, the prevalence of social capital in such settings is a direct result of voluntary associations that underlie their formation. The disadvantage of allowing such voluntary associations is that social stratification may, and often does, develop. Choice, social capital, and social equity are discussed within a framework that contrasts individualism and the common good. (Contains 59 references.) (RKJ)