This dissertation examines the way in which social capital, or productive networks, can be used to support downtown renewal. This case study examines the way in which Phoenix Community Alliance (PCA) and Downtown Phoenix Partnership (DPP)--two, critical downtown-focused organizations ostensibly founded for civic improvement--use social capital to advance downtown urban development initiatives. This case study also explores how and the extent to which new social capital is generated by PCA and DPP through the processes of planning, designing, and implementing downtown development projects and the kinds of initiatives this social capital enables, whether and how the focus of downtown Phoenix development has shifted over time, the challenges facing contemporary downtown development and role PCA and DPP might play in addressing these issues, and recommended strategies for advancing future downtown development through social capital that evolves as downtown needs change. This dissertation contributes to the general understanding of how pivotal groups responsible for impacting downtown development and quality of life can become more effective in their roles by examining how they create networks pivotal to advancing urban downtown renewal. Research findings illuminate how community development groups can more effectively use networks to inspire downtown improvement. Findings emphasize the need to engage a broader downtown community, including both emerging and established organizations and those who desire to contribute to a diverse and exciting heart or city core.