To understand the ASD diagnosis and treatment pathways for US families, N = 38 Mexican-heritage mothers were interviewed about how and when they obtained an ASD diagnosis for their children. Most children (84%) were diagnosed between two and three years old. One-third of mothers reported receiving four to seven referrals before diagnosis. Mothers identified multiple diagnosis circumstances including two diagnoses and services offered before diagnosis. A multiple case study design documented the diagnosis and treatment experiences of four representative participants. As compared to previous studies that utilized a deficit lens to rationalize barriers to diagnosis and treatment (e.g., parents not knowledgeable about ASD), these findings revealed a complex understanding of how structural barriers (e.g., immigration status), initial diagnosis rejection among caregivers, and abrupt service cancellation complicated the diagnosis and treatment process. Implications identified suggestions to optimize and streamline ASD diagnosis and treatment pathways for Mexican heritage families.