Though several excellent literature reviews and research syntheses have been conducted, and thoughtful frameworks and models have been proposed, I believe it is time for the evaluation field to tackle the "hard stuff" of evaluation capacity building (ECB). This entails engaging staff in ECB activities, building the evaluation capacity of leaders, focusing on learning transfer, and evaluating ECB efforts. In this brief article, I describe these four challenges and pose questions for both practitioners and researchers to consider and act upon.