Screening tools for autism spectrum disorders serve a vital role in early identification of all children who may need evaluation and support. Recent studies suggest that traditional methods used in this field to translate such tools may be insufficient for maintaining linguistic, construct, or technical equivalence, resulting in screening tools that do not meet high psychometric standards in the new population. This study implemented a rigorous translation and cultural adaptation process by translating the First Years Inventory v3.1 (Baranek et al. First year inventory (FYI) 3.1. University of North Carolina at Chapel Hill Chapel Hill, NC, 2003) for a US-based Spanish-speaking population. A description of this process is provided with results from data collected during each phase. The unique challenges that were identified and addressed are detailed for future translation teams.