Social capital, or access to resources through relationships with other people, can facilitate the socioeconomic mobility of youth living in low-income communities. This study examined whether parent-child relationship quality and participation in a youth development program (YDP) were associated with gains in hope for the future, and whether those associations were mediated by parent social capital (i.e., access to resources through relationships with parents) and non-parent social capital (i.e., access to resources through relationships with people other than parents). The sample included 216 participants of one YDP program, Cool Girls, Inc., and 92 comparisons. Path analyses indicated that program participation for over one year predicted gains in non-parent social capital, and increases in both parent and non-parent social capital predicted increases in hope for the future. There was also evidence that first-year program participation was associated with gains in hope for the future. Implications for practice and research are discussed.