A growing number of nonprofit organizations have been created by immigrants and refugees to serve their communities in North America. These immigrant- and refugee-led organizations (IRLOs) work to provide services and meet a variety of needs, while at the same time building the infrastructure of these communities. Through a grant from the W. K. Kellogg Foundation Innovation Fund, Fieldstone Alliance initiated the two-year project in January 2004. The goal of Nexus was to enhance the knowledge and skills of capacity builders across North America in working with immigrant- and refugee-led organizations. The Nexus Project had two main components: research on capacity building with IRLOs and formation of a peer learning community among those who build the capacity of these organizations. This report draws three broad lessons for the capacity building field, with implications for the funding community, IRLOs, and capacity builders: effective capacity building takes time, which requires resources; more immigrant and refugee capacity builders are needed; and capacity builders need continuous learning and development. The Introduction describes the formation of the Nexus Project, its goals, and its working definitions. Chapter 1 describes the factors that result in effective capacity building with immigrant- and refugee-led organizations. Chapter 2 presents case studies from each of the Nexus partners. Each case study illustrates a practice used by Nexus partners when working with IRLOs. Chapter 3 details lessons Nexus partners learned through the course of this project. It further states implications of these lessons for those who fund work with IRLOs, for IRLO leaders, and for capacity building providers. The Appendices include a summary of IRLO research conducted by Wilder Research Center specifically for Nexus; a bibliography; and descriptions of the organizations and individuals who contributed to this report.