Service learning, a high-impact pedagogy, involves integrating academic outcomes with service to the community. The success of service learning experiences depends on the development of mutually reciprocal relationships between students, instructors, and community partners, ensuring equitable benefits for all stakeholders. To explore how relationship-building and growth are supported in computer and information science (CIS) service learning, we conducted semi-structured interviews with 13 informants--each a faculty, student, or community partner who participated in one of five computer or information science service learning courses. Our analysis identified three factors that were most crucial in supporting the formation of relationships among stakeholders: infrastructuring the relationship, valuing technical and other expertise equitably, and integrating soft skills and technical skills. Based on these findings, we discuss how growth, an important outcome of relationship-building and equitable service learning experiences, can be supported and assessed in CIS service learning experiences.