Methods to make measurement both valid and reliable in a transcultural setting are exemplified from a study done in Goa, India, to examine symptom prevalence in two groups, Christians and Hindus. Access to Goan culture was gained through field consultants, library research, and field observations. The interview instrument consisted of multiple-choice questions on social characteristics, general health status, and symptoms, Two forms, one in Portuguese, the other in Konkani, were made equivalent in meaning by a translation and back-translation. Symptoms were defined within the culture. The Langner scale was used for questions on symptoms. Reliability and validity checks were included in the instrument itself as well as its translation and use. Bilingual physicians and bilingual experts in Goan culture worked in the instrument construction. Bilinguals and monolinguals were pretested and probed. Other steps involved: careful wording of questions, use of redundancy and decentering, provision of context, warning translators against biases and supervising their work, approaching subjects in local ways and through local leaders, and having the instrument administered by a bilingual physician.