A Spanish translation of the Autism Detection in Early Childhood (ADEC-SP) was administered to 115 children aged 15-73 months in Mexico. In Phase 1, children with Autistic Disorder (AD), a non-Pervasive Developmental Disorder (PDD) diagnosis or typical development were assessed with the ADEC-SP by a clinician blind to the child's diagnostic status. In Phase 2, a referred sample of children was assessed with the ADEC-SP, Childhood Autism Rating Scale (CARS), Autism Diagnostic Interview-Revised (ADI-R) and Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV), and typically developing children were assessed with the ADEC-SP and CARS. Psychometric properties relating to validity and reliability were addressed. Sensitivity and specificity levels for the ADEC-SP ranged from 0.79-0.94 and 0.88-1.00 respectively. In a subgroup of toddlers aged 19 to 36 months the ADEC-SP correctly identified 17 of the 18 children with a diagnosis of a PDD, and no child without a PDD diagnosis was misdiagnosed. The ADEC-SP shows promise as a Level 2 screening instrument for use in Mexico. (Contains 6 tables and 3 notes.)