The More Than Brides Alliance (MTBA) implemented an intervention in India, Malawi, Mali and Niger from 2017 to 2020. The holistic community-based program included girls' clubs focused on empowerment and sexual and reproductive health knowledge; work with parents and educators; community edutainment events; and local-, regional-, and national-level advocacy efforts related to child marriage. Using a cluster randomized trial design (India and Malawi), and a matched comparison design (Niger and Mali), we evaluated the effectiveness of the program on age at marriage among girls ages 12-19 in intervention communities. Repeat cross sectional surveys were collected at baseline (2016/7), midline after approximately 18 months of intervention (2018), and endline (2020). Impact was assessed using difference-in-difference (DID) analysis, adjusted for the cluster design. We find that the intervention was successful at reducing the proportion of girls ages 12-19 married in India (-0.126, p < .001). Findings in the other countries did not show impact of the intervention on delaying marriage. Our findings suggest that the MTBA program was optimized to succeed in India, in part because it was built on an evidence base that relies heavily on data from South Asia. The drivers of child marriage in India may be substantially different from those in Malawi, Mali, and Niger and require alternate intervention approaches. These findings have implications for those designing programs outside of South Asia and suggest that programs need to consider context-specific drivers and whether and how evidence-based programs operate in relation to those drivers. Trial registration: This work is part of an RCT registered August 4, 2016 in the AEA RCT registry identified as: AEAR CTR-0001463. See: https://www.socialscienceregistry.org/trials/1463., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Melnikas et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)