This study of social capital employs data from the Longitudinal Study of Adult Learning (LSAL), funded by the National Center for the Study of Adult Learning and Literacy (NCSALL) and conducted at Portland State University to increase understanding of the learning process of adults with limited formal education. It provides longitudinal data on how people continue learning in multiple contexts--through formal adult education programs and in their daily lives. This paper is presented in two sections. The first is a theoretical exploration of the intersections of critical literacy, adult learning, and social capital theories. The intent of this discussion is to introduce key concepts from multiple disciplines and develop a synthetic model of social capital influences on lifelong learning (SCILL) in which adults construct their social environment and the discourses that influence their learning strategies. The second section empirically tests a piece of the SCILL Model related to the structural and discursive dimensions of social capital, using data from the first wave of the LSAL. Multiple measures of social capital are detailed. The author argues that in addition to the structural dimension of social capital, local discourse generated through interaction is an interpretive dimension of social capital. The discussion ties the empirical and theoretical elements, offering implications for the study of adult education participation in adult education for research on social capital. Appendices include: (1) Longitudinal Study of Adult Literacy Study Design; (2) Instrument Items from LSAL Wave 1; (3) Confirmatory Factor Analysis of Lifelong Learning; (4) Tables of Descriptive Statistics and Univariate Analyses of Indicators; (5) Items Parameters in Final Models; and (6) Model Calibration. (Contains 18 tables, 3 figures, and 6 footnotes.)