Examining nonprofit revenue diversification is important not only in understanding nonprofit financial management dynamics but also in informing nonprofitfinancial sustainability. This study draws on nonprofit financial management theories to propose three research questions, and develops and empirically tests an integrated model that investigates how contextual factors – organizational structure and capacity,managerial experience, fund development effort and investment, and operating environment – affect nonprofit revenue diversification and financial sustainability. Questionnaires were administered to executive directors of 1,115 New Jersey human services and community improvement organizations. Using data from 501 responding organizations, this study found certain organizational and environmentalcharacteristics have a significant influence on nonprofit revenue diversification. As expected, some capacity, management, investment and environment measures have a positive impact on funding variety, but fewer measures have a positive effect on revenue balance. Multiple regression analyses reveal that most of the hypotheses regarding predictors of financial sustainability are not confirmed which suggests that the research model does not include other factors that significantly impact nonprofit financial sustainability. Major findings of the study include: (a) organizational structure and capacity, such as employee size, years of operation, board involvement, and internal development,are positively related to nonprofit revenue diversification, particularly funding variety; (b) managerial factors, including management’s attitude toward revenue diversification, management’s influence on fund development strategies, and recent operational cutbacks, have significant impact on funding variety, but less so on revenue balance; (c) using designated fund development staff and developing good relationship with outside stakeholders enhance revenue diversification; and (d) revenue diversification does nothelp organizations maintain financially sustainable. Although these findings are only suggestive, this study is a significant step forward in the development of a theory of nonprofit financial performance including the analysis of revenue diversification which will lead to a better understanding of a number of topics that have been understudied and thus not well understood.