Background:The general development assessment test (EVADE) for children and adolescents aged 6-14 years is the only national screening tool for development assessment of school-age children and adolescents. This article presents the results obtained after applying the face validity process to the test, the handbook, and the standardized materials. Methods: An exploratory, descriptive study was conducted with a quantitative-qualitative methodology. The EVADE test was applied to a sample of 730 children and adolescents between 6 and 14 years of age, for which the expert judgment technique was used. Data analysis was carried out through a psychometric analysis of the items and by the triangulation method. Results: From the 730 participants included, 44.5% were from rural areas (n = 325) and 55.4% from urban areas (n = 405), of which 51.7% (n = 378) of females and 48.2% (n = 352) of males were assessed by the test. The difficulty level and discriminative effectiveness quotient of the items were calculated, which, together with the experts' findings, resulted in 22-item modifications and the creation of four new items in the cognitive and language areas. The qualification by areas also changed, improving the handbook and creating new materials. Conclusions: This research provides a validated screening test for the child and adolescent population, which was included in the Costa Rican comprehensive childcare public policy. However, subsequent validation processes are recommended to improve specific areas, such as motor skills and social-affective development.