This study examined the effects of social capital upon the economic adaptation of 2336 primarily Latin American and Asian immigrants and refugees residing in Miami-Fort Lauderdale and San Diego. A multivariate, cross-sectional survey design was used. It was found that social capital, as indicated by respondents' social networks, workplace ethnic composition, informal assistance and formal assistance received, had minimal impact upon economic adaptation, as indicated by employment status, public assistance utilization, and earnings, after controlling for human capital, household composition, citizenship, English ability, and gender. The findings cast doubt upon the theory of social capital as a determinant of immigrant and refugee economic adaptation, while supporting the important role of human capital, citizenship, English ability, and gender. [ABSTRACT FROM AUTHOR]