The main purpose of this study is to analyze whether quality of preschool classrooms relates to 4- and 5-year-old children developmental outcomes. The study was conducted in 60 classrooms in Porto Metropolitan Area, Portugal. Children (N=215) were evaluated in the literacy, math, and behavior domains. Preschool quality was assessed through classroom observations using the ECERS-R and the Early Language and Literacy Classroom Observation. Global classroom quality although relatively low, predicted children's literacy skills and behavior but not math skills. Quality of language and literacy environment was not consistently related to child outcomes. Mother educational level stood out as consistently predicting most of child developmental outcomes. The relevance of these results is discussed considering the Portuguese educational scenario, in the realm of an international context. (author abstract)