In 1996, we launched a panel study in the Chitwan Valley of Nepal to investigate the influence of social contexts on population processes. Twenty years later, the Chitwan Valley Family Study (CVFS) is still underway, with a population-based sample of 10,000 people. Over time, the focus of the CVFS has expanded to other areas including agricultural production, migration, and labor force participation. In 2016, the CVFS expanded again, launching its most ambitious data collection effort yet—the collection of psychiatric phenotypes and biospecimens to investigate the role of genetics and the environment in producing common psychiatric disorders. This case study describes our 3-year-long mixed-methods approach to develop a clinically validated survey questionnaire to measure psychiatric disorders in Nepal. We detail our process to translate and adapt a widely used mental health survey from English into Nepali and validate the instrument's ability to diagnose psychiatric disorders in Nepal. We also describe lessons we learned along the way and offer some advice. We hope that this case will help other researchers planning to take an existing instrument and adapt or translate it to another culture or language. We do not intend this study to be used as a set of instructions for translating instruments. Instead, we encourage you to read our case study with your study in mind, drawing parallels and noting dissimilarities along the way, review the vast literature on the topic, and then design your own translation and validation process to meet the needs of your unique study.