Published in The International Journal of Reasearch on Service-Learning and Community Engagement, this article focuses on medical students increasingly seeking global health service-learning opportunities; yet, the impact of these interventions is often not assessed. In this article, the authors describe a model for global health service-learning programs as well as a pilot tool for assessing program impacts on populations traditionally difficult to evaluate. Specifically, a group of medical students from the United States, in collaboration with local health officials and a global NGO, successfully implemented a training program for parteras, or traditional birth attendants, in Mexico. The training included educational objectives from the Ministry of Health. A pilot assessment tool was developed which included oral pretest and posttest self-reported knowledge and task-specific ability in 12 program-specific categories. The assessment was administered in an effort to determine educational impact: parteras, who were receptive to students as teachers, reported increased knowledge and skill in all topics except nutrition and postpartum care. The results of the assessment suggest that undergraduate medical students, when collaborating with a facilitating organization, community-based healthcare workers, and local ministries of health, can improve lay birth attendants’ confidence in basic obstetric knowledge and skills through global service-learning. Moreover, creative assessments are required to understand impacts on difficult to access populations.