Financial sustainability remains a critical challenge for Civil Society Organization (CSOs) around the world. Although a variety of toolkits and research papers exist examining specific sustainability strategies , many CSOs continue to struggle to develop and maintain the resources needed to carry out their missions. The Facilitating Financial Sustainability (FFS) activity was launched in 2017 to develop and test ways that different actors (including donors, policymakers, intermediary organizations, and CSOs themselves) can work together to improve the factors that drive financial sustainability for local organizations in different developing world contexts. This paper covers an analysis of the drivers of CSO sustainability based on interviews with CSO representatives. This represents one part of the three-part FFS research series, and is best considered alongside the other papers in the series to give a holistic perspective on CSO financial sustainability: "Funder Approaches to Facilitating CSO Financial Sustainability", which provides an overview of the funding landscape for financial sustainability in the six countries included in the study, and "Facilitating Financial Sustainability: Synthesis Report", which brings together the key findings from both other papers in the series.