With support from the Bill & Melinda Gates Foundation and in partnership with the International Initiative for Impact Evaluation (3ie), ThinkWell supported a review on the implementation cost of cluster randomized controlled trials (CRCTs). The goal of this evaluation was to better understand the cost drivers of CRCTs by collecting and aggregating expenditure data from a subset of recently published CRCTs globally. Working with research teams from finalized CRCTs, ThinkWell analyzed expenditure data to understand what drives the cost of CRCTs in different geographic areas. The results of this analysis provided donors with a robust data set on which to base their future funding decisions CRCTs.