This project will develop a novel post-hoc evaluation approach that can mine information from “dilute intervention trials." Dilute intervention trials are those that may have produced null results because of lower than expected recruitment of participants who could benefit from the intervention. Dilute intervention trials are fairly frequent in real-world evaluation. The project has three aims: 1) to assemble an inventory of randomized pilot programs implemented in Kaiser Permanente over the past five years that experienced dilute uptake in the intervention arm, including obtaining patient rosters capturing both “as randomized” and “as treated” status for intervention and control groups; 2) to develop and pilot a methodological approach to post-hoc recruitment for one dilute intervention (using the patient roster) and test the piloted approach using patient rosters from other dilute interventions; and 3) to develop guidance to evaluators and delivery system managers through written publications and oral presentations.