Substantial evidence endorses the early assessment of cognitive development to promote children's developmental health and well-being. Especially in the Brazilian context, there is a paucity of standardized screening and assessment tools with normative data to evaluate young children. This study provided initial reliability and validity evidence to support the use of the Cognitive Scale of the Dimensional Inventory for Child Development Assessment (IDADI) in a Brazilian sample of 1,174 4 to 72-months-olds. The inventory includes 106 maternal report items that assess increasingly sophisticated cognitive skills attained by children. Rasch analysis indicated excellent internal consistency of scores and optimal participant discrimination. Person separation was 10.67 and reliability was 0.99. Items sufficiently spanned cognitive abilities with an item separation of 35.81 and reliability of 1.00 (mean infit=0.95 [SD=0.28], mean outfit=1.63 [SD=1.97]). Items' hierarchy was consistent with expectations regarding the developmental difficulty of various cognitive skills. Cluster analysis indicated different patterns of association between cognitive development and age, and a cluster predominantly of children with developmental disorders. IDADI scores correlated with relevant criteria variables, such as age, developmental diagnosis, maternal education, and the Strengths and Difficulties Questionnaire, supporting the use of IDADI as a psychometrically sound measure of cognitive development.