Certain constructs influence relationships within community organizations and the not-for-profit sport sector. This qualitative study identified influences on relationships and determinants of successful and unsuccessful partnerships and determined the application of 28 constructs derived from literature on relationship marketing, education partnerships, and health and community service partnerships. Results of interviews with 15 personnel from Australian sport, education, and health and community service agencies indicated that partnerships achieve goals that the individual partners could not achieve individually, foster innovation, and share knowledge and expertise. A key feature of successful relationships is complementary expertise and knowledge. Factors contributing to an unsuccessful relationship include poor communication, incompatible management styles, lack of commitment (including time), staff turnover, and lack of satisfaction. Key constructs that influence relationships are appropriate partners, commitment, communication, cultural/management style, funding/resource allocation, and satisfaction. This study also identified the need for community agencies to make conscious effort to manage their relationships. Not-for-profit sport organizations did not practice relationship management and tended to take the development of their relationships for granted. Focusing on the constructs that influence relationships can assist sport managers to derive more positive outcomes from their relationships.