The Battery for Rapid Evaluation of Cognitive Functions (Batterie Rapide d'Evaluation des Fonctions Cognitives: BREV) was designed to provide health professionals with a quick clinical tool for screening acquired and developmental cognitive deficits in children aged 4 to 8 years. The BREV explores oral language in both its expressive and receptive forms, non-verbal functions, attention, verbal and visuo-spatial memory, and main learning acquisition. Results of the first phase of validation are presented in this report consisting of internal validity measurements gained by testing 500 normally developing school children (257 females, 243 males; mean age 6 years 7 months, SD 1 year 6 months. The validation provides appropriate values for each of the 17 subtests assessing cognitive functions (oral language, non-verbal abilities, attention and memory, educational achievement) in 10 age groups, from 4 to 8 years of age. All subtests with the same content for any age revealed values which increased significantly with age. Interreliability was tested in a retest for 70 children and scores obtained on retesting correlated significantly with initial values. The BREV is a reliable test with carefully established normative values, appropriate for preschool and school-age children.