Evaluation capacity building (ECB) is an essential element for generating credible and actionable evidence on Extension programs. This paper offers a discussion of ECB efforts in Cooperative Extension and how such efforts enable Extension professionals to collect and use credible and actionable evidence on the quality and impacts of programs. Sufficient investments in ECB, both at the individual and organizational levels, can better equip Extension to advocate for and make changes to programs, advance as a learning organization, and have a more powerful impact on communities. Furthermore, as Extension program stakeholders often have varying perspectives on the credibility of evidence, these perspectives must also be accounted for in efforts to build Extension's evaluation capacity. Intentional investments in ECB efforts provide an opportunity for Extension to further deepen and expand impact, positioning programs to most effectively and positively benefit individuals and communities.