Program evaluation can play a critical role in supporting high quality implementation of social programs to help them achieve their goal of social impact. Evaluation scholars have developed a wide range of strategies to help build programs' internal evaluation capacity in an effort to support meaningful use of evaluation. However, the evaluation capacity building literature has predominantly focused on capacity to "do" evaluation rather than capacity to "use" evaluation and there is a lack of understanding of the organizational characteristics that facilitate productive use of evaluation for learning and data-driven decision-making. The current study used a sequential-explanatory mixed methods design to examine the relationship between evaluation capacity and use and explore the extent to which organizational learning capacity (OLC) influences the degree to which organizations use evaluation for quality improvement. The study examined these relationships within the context of Expanded Learning Programs (ELPs) for school-aged youth. The first study tested the hypothesized relationships between evaluation capacity, OLC, formative evaluation of program quality, and use of evaluation for program improvement via a statewide survey of program directors. Study One found that higher evaluation capacity was associated with greater use of evaluation for program improvement and found that evaluation of program implementation and quality was the mediating mechanism that linked an organization's evaluation capacity with their use of evaluation for program improvement. OLC was found to be a direct predictor of evaluation use above and beyond evaluation capacity. The second study examined the specific organizational behaviors associated with high levels of formative evaluation and use of evaluation for program improvement through in-depth interviews with multiple representatives of exemplar agencies from Study One. Study Two found that agencies with high levels of formative evaluation practice and use for program improvement engage in organizational behaviors that are reflective of high levels of OLC. The results of these studies contribute to the extant literature on the factors that facilitate evaluation use in social programs and provide meaningful information to guide policy and practice in the ELP context. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]