There is a pressing need to improve early detection of Autism Spectrum Disorders (ASD) so that families can access intensive, appropriate intervention services as early as possible. However, studies indicate that important racial and ethnic disparities exist in the identification and diagnosis of children with ASD in the US, which impact access to services. Very little research is available on ASD from developing countries. This research investigation is a foundational study of early social communication markers of ASD in children from two diverse cultures from two different countries- Latino immigrants in Southeastern US and the KwaZulu-Natal (KZN) province of South Africa. These two regions were selected to inform future epidemiological research on ASD in diverse populations both in the US and other developing countries. Children in this study will range from 18 to 36 months of age. This study will use an observational case-control research design to compare early behavioral markers of ASD in 15 children who end up with a confirmed diagnosis of ASD from a predominantly Latino immigrant population in Collier County, Florida in the southeastern US (ASD-US1), 15 young African children from KZN who end up with a clinical diagnosis of ASD (ASD-Africa), and matched control children from Leon County, Florida, who have been diagnosed with ASD by the FIRST WORDS(R) Project (ASD-US2). The three groups of children with ASD will be compared to groups of typically developing (TD) children from each site (TD-US1, TD-Africa, TD- US2). Children will be recruited with autism-specific screening tools adapted for these low-resource settings. We will first conduct a series of focus groups to adapt the screening and diagnostic tools to be culturally appropriate and to understand the influence of culture on expectations of children and understanding of disabilities including ASD. Social communication markers of ASD will be compared during two different video recorded observation methods-structured observations using systematic sampling procedures and naturalistic observations of everyday activities. A clinical diagnosis of ASD based on the DSM-IV diagnostic criteria will be confirmed or ruled out by experienced clinicians using the Autism Diagnostic Observation Schedule. These findings will provide information about the relationship between culture and ASD in order to advance science on the heterogeneity of ASD and have important implications for informing research on genetic and environmental mechanisms of ASD. This research study is pivotal to our long term aims of adapting screening and diagnostic tools for epidemiological research and strengthening in-country and global collaboration to build the capacity in low-resource settings for appropriate accessible early intervention. PUBLIC HEALTH RELEVANCE: The expected outcomes of this study will have significance for the field by identifying behavioral markers that distinguish young Latino children in the Southeastern US and African children from KwaZulu-Natal with Autism Spectrum Disorders (ASD) from children with typical development from those cultures. It is important to investigate the relationship between culture and ASD in order to advance science on the heterogeneity of ASD. Cultural differences may be evident in the behavioral phenotype of ASD, recognition and interpretation of symptoms by caregivers, the decisions parents make regarding evaluation and treatment, and interactions between families and the healthcare system. The results of this research will lead to culturally sensitive screening and evaluation methods that may decrease the age at which all children with ASD are diagnosed.