In Latin America, scales have been built to assess Early Child Development (EChD), most of them for direct evaluations. In Chile, the Psychomotor Development Evaluation Scale (EEDP) and the Test of Psychomotor Development (TEPSI) were developed in the 70's and 80's and are still used in different Spanish-speaking countries, but have not been updated or revalidated. In response to the need for a new instrument built in Chile for the evaluation of EChD on a large scale, the Test of Early Learning and Development (TADI-2, for its acronym in Spanish) was built and standardized between 2009 and 2012. This was updated and strengthened between 2018 and 2023 as TADI-2. Objective: To describe the main methodological requirements considered in the construction of a health measurement instrument and, in this context, to analyze the validity of the TADI-2. Development: The rigorous validation process of the TADI-2 stands out, complying with the standards of content selection, standardization, reliability, validity in different sociocultural and ethnic environments, low cost, easy application and open use. Sensitivity for the global score in 4- and 5-year-olds was very good and, in younger children, moderate. Conclusions: : The gathered evidence shows that the TADI-2 may be implemented for EChD screening through direct assessment of children under 6 years of age in Chile and the rest of the continent. It is recommended to continue studying the instrument in larger samples to know the consistency of the results in complementary and population-based studies.