Although nonprofit organization (NPO) leaders play crucial roles in society, financial distress and vulnerability are common for many NPO leaders, with some NPOs closing as a result of these conditions. The purpose of this single-case study was to explore the diversification strategies used by 10 leaders and senior staff of an NPO in the mid-Atlantic region of the United States through the conceptual lens of Markowitz's modern portfolio theory. Data were collected through in-depth semistructured interviews and analysis of organizational documents, internal archival data, social media, literature, and online databases. Through thematic analysis, 7 revenue diversification themes emerged: adding revenue streams; establishing an operating reserve; establishing positive financial performance; achieving financial stability, sustainability, organizational capacity, and organizational resilience; using transparency; achieving efficiency and organizational effectiveness; and using a marketing strategy. Additionally, 7 key themes emerged: documenting and implementing systematic processes, developing an approach to process improvement, implementing cross-department action plans, increasing transparency, reversing the adverse trend in forum participation, building a data-management system, and increasing individual and organizational capacity. These findings have implications for positive social change, in that they may offer NPO executives new insights and strategies to support revenue diversification, thereby helping them to reduce volatility in funding, decrease financial risk, avoid dependence on sole-source revenue, and identify opportunities to increase flexibility in support of organizational goals and objectives to increase services.