For members of the dominant culture, libraries produce largely positive affective responses (Farkas). However, researchers and practitioners in the field of library science have identified a need to make library resources more accessible to patrons from marginalized communities who are excluded from library spaces by institutional policies and structural constraints that reproduce systemic inequities (Hughes-Hassel et al.). Research suggests that there is an important link between library services and community rhetorical empowerment that can help build social capital, but there has not been sufficient investigation into the relationship between library programming and social capital (Strover et al.). My dissertation project seeks to intervene in this gap by using a rhetoric and composition lens to understand the role that the circulation of both library materials and ideas about literacy plays in increasing individual empowerment and building individual social capital among marginalized community members. My findings suggest that empowerment is both material and affective, requiring people to have access to the resources they need but also to perceive themselves as participants in their own information building. I investigate rhetorical and literal understandings of how literacy is enacted in mobile libraries that emphasize access as the primary motivator for their services, using case studies that span a variety of types of mobile library programs. First, I examine Dolly Parton's Imagination Library and the Little Free Library Program as examples of large-scale public programs that are not geographically bounded or affiliated with a public library. Then, I move to mobile library programs that serve incarcerated people in a variety of geographic locations. These include Freedom Reads, Books Beyond Bars, Books through Bars, the Prison Book Program, and the Prisoners Literature Project. Although these programs serve the same population, they have distinct ways of operating that offer important insight into the rhetorical links between literacy and empowerment. Finally, I address public library bookmobile programs using one specific case study that focuses on a public library bookmobile in Austin, Texas. Altogether, my analysis of these examples shows that mobile library programs function rhetorically to circulate definitions of literacy that facilitate patron empowerment and build individual social capital. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]