Sustained attention influences academic achievement because maintaining focus on a task for an extended period supports the acquisition of new skills. Investigating the development of sustained attention has been an important topic in educational and psychological research. This study includes secondary analysis of data collected as part of a larger project that provided opportunities for children to learn chess after school. This study analysed data related to sustained attention, which was measured by the Continuous Performance Task across one academic year in a predominantly African American sample. This sample consists of 149 participants (n = 66 females, M age = 9.57 years, SD = 0.89 years) attending schools in high poverty communities in the USA. To the best of our knowledge, this study is the first to examine changes in sustained attention in ethnic minority students from high poverty areas using a longitudinal design. A repeated-measures ANOVA was used to conduct statistical analysis. The results indicated that participants’ performance on the sustained attention task improved significantly from the beginning to the end of the school year. Although past studies have examined changes in sustained attention in children using this same task, no studies have used a repeated-measures design in ethnic minority samples. These findings demonstrate the possibility that sustained attention improves continuously in children, despite the difficulties associated with growing up in high poverty environments.