Evaluation capacity building (ECB) is a practice that can help organizations conduct and use evaluations; however, there is little research on the sustainable impact of ECB interventions. This study provides an empirical inquiry into how ECB develops sustained evaluation practice. Interviews were conducted with 15 organizational leaders from non-profits, higher education institutions, and foundations that “bought in” to ECB and were at least six months removed from an ECB contract. The result of this work highlights how sustained evaluation practice developed over time and what these practices looked like in real-world settings. A developmental, iterative cycle for how ECB led organizations to sustain evaluation practice emerged around key components to sustainability. First, leadership supported ECB work and resources were dedicated to evaluation. Staff began to conduct and use evaluation, which led to understanding the benefits of evaluation, and promoted value and buy-in to evaluation among staff. Common barriers and emerging sustainability supports not previously identified by ECB literature—the “personal” factor and ongoing ECB practitioner contact—are described. Practical tips for ECB practitioners to promote sustainability are also detailed.