Stigma toward people with mental illness and substance use problems is a significant global concern, and prevents people with these conditions from accessing treatment, particularly in primary health care (PHC) settings. Stigma is a cultural phenomenon that is influenced by particular contexts and can differ by country and region. The majority of stigma research focuses on Europe or North America leading to a lack of culturally relevant stigma research instruments for the Latin American context. The present study describes and discusses the methodology for cross-culturally adapting four stigma measurement scales to the Chilean context. The cross-cultural adaptation process included nine phases: (1) preparation; (2) independent translations; (3) synthesis 1 with expert committee; (4) focus groups and interviews with researchers, PHC professionals, and PHC users; (5) synthesis 2 with expert committee; (6) independent back translations; (7) synthesis 3 with expert committee; (8) pilot with PHC professionals; and (9) final revisions. The adaptation process included an array of diverse voices from the PHC context, and met three adaptation objectives defined prior to beginning the process (Understandability, Relevance, and Acceptability and Answer Options). The resulting, culturally adapted questionnaire is being validated and implemented within PHC settings across Chile to provide in-depth insight into stigma among PHC professionals in the country. The authors hope it will be useful for future research on mental illness and substance use stigma in similar settings across Latin America.