Little research has been conducted on behavioral characteristics of children with autism spectrum disorder (ASD) from diverse cultures within the US, or from countries outside of the US or Europe, with little reliable information yet reported from developing countries. We describe the process used to engage diverse communities in ASD research in two community-based research projects—an epidemiologic investigation of 7- to 12-year olds in South Korea and the Early Autism Project, an ASD detection program for 18- to 36-month-old Zulu-speaking children in South Africa. Despite the differences in wealth between these communities, ASD is underdiagnosed in both settings, and generally not reported in clinical or educational records. Moreover, in both countries, there is low availability of services. In both cases, local knowledge helped researchers to address both ethnographic as well as practical problems. Researchers identified the ways in which these communities generate and negotiate the cultural meanings of developmental disorders. Researchers incorporated that knowledge, as they engaged communities in a research protocol, adapted and translated screening and diagnostic tools, and developed methods for screening, evaluating, and diagnosing children with ASD. Autism Res 2012, 5: 201–210. © 2012 International Society for Autism Research, Wiley Periodicals, Inc.