From 2010 to 2012, the city of Rio de Janeiro initiated a large-scale project to evaluate the development of children who were enrolled in daycare centers and public preschools. The evaluation of child development was performed annually, with an average of 60,000 children in more or less 80 percent of the daycare centers and public preschools in the city. After receiving specific training, professionals at each institution (e.g., teachers and caregivers) applied the Ages and Stages Questionnaires (ASQ-3 and ASQ:SE) to screen for risk factors (e.g., developmental delays) with regard to the major markers and milestones of child development. However, in the Brazilian context, there is a lack of studies that have investigated the psychometric properties of the Brazilian version of the ASQ:SE. Moreover, a dearth of studies has discussed the results of both the ASQ:BR and ASQ:SE with regard to longitudinal assessments, gender differences, and incorporation of the statistical results into public policies. That said, the present thesis had the following objectives: (1) to investigate the main psychometric properties of the ASQ:SE using both Classical Test Theory (CTT) methodology and Item Response Theory (IRT) and (2) to present an overview of child development in daycare services using the data that were gathered from this longitudinal project. Thus, this thesis comprises five articles in which the following studies were conducted. Initially, based on CTT, the factor structure of the ASQ:SE was estimated using Cronbach s, and preliminary cutoff points were computed, based on means and standard deviations. The second article extended investigation of the factor structure of the ASQ:SE and in the third article, a multidimensional IRT model was used for two purposes: (i) to confirm the dimensionality of all scales of the ASQ:SE and (ii) to verify its item characteristics. In the fourth and fifth article, the focus partially shifted from psychometric properties to the preliminary results of a longitudinal evaluation of children who were assessed over two or three consecutive years. The overall results provide evidence of the validity, reliability, and utility of the ASQ:SE and suggest that children who are enrolled in Brazilian/Rio de Janeiro s public daycare centers, despite environmental adversity, are not at risk of serious developmental delays.