Mixed methods research is increasingly common in emergency medical services, but methodological expertise among prehospital researchers has been found lacking. The purpose of this article is to describe unique challenges that the authors encountered in the application of mixed methods to a multisite, international study of prehospital language barriers. Lessons learned include the role of formative research in identifying cultural and organizational norms that affect researcher engagement with emergency medical service agencies, the necessity of developing approaches for member checking and assessing respondent validity, and the importance of promoting mixed methods as a rigorous methodology in international settings.