Decades of research have established that racial ethnic minority, low-income, and/or non-English speaking children with autism spectrum disorder (ASD) are diagnosed later than white children, and their families experience greater difficulty accessing services in the USA. Delayed access to timely diagnosis and early intervention may impact child outcomes and family quality of life. Despite their cognition of these disparities and their significant impact on the lives of those affected, explanations for the barriers experienced by underserved families are elusive, likely due to the complex interaction between structural and family factors. This study used qualitative methods to gather family and provider perspectives of perceived barriers and facilitators to obtaining an ASD diagnosis and accessing ASD-related services for underserved families. Themes from focus groups and interviews with families from three cultural groups (black, Hispanic/Latino, and Korean) and three primary languages (English, Korean, and Spanish) highlight specific barriers related to family, community, and systemic challenges as well as facilitators to accessing care for these populations. Family experiences are expanded upon with viewpoints from the providers who work with them. Recommendations are made for reducing disparities in the existing ASD service system including increasing professional, family, and community education; increasing culturally responsive care; improving provider-family partnerships; and addressing practical challenges to service access.