Word-level reading is strongly associated with phonological processing. The aim of this study was to investigate the effects of cognitive and environmental variables on word reading performance. Our sample consisted of 185 fourth-grade students. Linear regression analyses were used to investigate the role of the following variables as potential predictors of word reading accuracy and fluency: phonological processing (phonological awareness, rapid automatized naming, and phonological memory); verbal fluency; working memory; socioeconomic status and an indicator of school quality (IDEB) in Brazil. Phonological awareness and rapid automatic naming were the best predictors of reading, supporting the role of phonological processing as a key contributor to the lexical aspects of reading, beyond the early years of literacy acquisition. Environmental variables were significant predictors of irregular word reading (socioeconomic status) and fluency (IDEB), corroborating multicomponent models of reading performance. The present findings demonstrate the complex interplay of factors underlying reading performance and highlight the importance of a multidimensional approach to the study of reading.