Environmental nonprofits (ENPOs) play vital roles in addressing environmental problems. To succeed, ENPOs must be adept at developing and maintaining successful partnerships with businesses, government agencies, and other NPOs. Even though evidence suggests ENPOs rely on these partnerships more than NPOs in other cause areas, however, relatively few empirical studies have focused on how they find success. This study explored what types of partnerships are common, what contributes to perceived success, and what communication tools ENPOs rely on. In addition to providing important descriptive information about the partners ENPOs value most, the results revealed that perceived success was closely linked to relational framing of conversations between partners, but not organizational features or homophily. Implications for ENPOs and future studies of NPO partnerships are discussed. [ABSTRACT FROM AUTHOR]