We introduce the Symbiotic Sustainability Model (SSM) as a macrolevel explanation of nongovernmental organization (NGO)-corporate alliances. The SSM presents NGO-corporate alliances as distinct interorganizational communication relationships, symbolized to stakeholders to influence the mobilization of capital. We contend that alliance partners communicatively co-construct the alliance with stakeholders in order to mobilize economic, social, cultural, and political capital. By focusing on the communication of alliances' existence and character, new propositions emerge concerning the role of communication, capital mobilization resulting from NGO-corporate alliances, NGOs and corporations' choice(s) of alliance partner(s), the number of partners with whom organizations are likely to communicate, and potential risks and rewards. The model is illustrated using the Rainforest Alliance and Chiquita Better Banana program as an abbreviated case study.