The main purpose of this study was to validate the curriculum-based measure "Indicadores de Progreso de Aprendizaje en Matemáticas" (IPAM [Indicators of Basic Early Math Skills]) in a local, Spanish-speaking context. This tool has been designed to identify first-grade students at risk for mathematics learning disabilities. The IPAM includes five measures (i.e., quantity discrimination, multi-digit computation, missing number, single-digit computation, and place value), which were analyzed as single measures and as part of a composite measure. In this study, 176 first graders were administered the curriculum-based measurement IPAM at the beginning, middle, and end of the school year. The results showed that the composite measure of the IPAM was the best indicator of risk status. Reliability and concurrent and predictive validity results were adequate. Furthermore, receiver operating curve analysis and hierarchical linear model supported the capacity of the IPAM to correctly identify students' risk status and growth rate during first grade.