This study examined whether optimism is a unique predictor of fourth and fifth graders' academic performance. The few studies that have examined this relationship with students in middle childhood have ignored relevant covariates and have focused on higher socioeconomic White students. In the present study, we examined the relationship between optimism and reading and math achievement after controlling for previous achievement, socioeconomic status (SES), gender, teacher, executive functioning, positive classroom behaviors, perspective taking, and empathic concern in a sample of predominately low SES Latinx students in fourth and fifth grade. Optimism was one of the strongest unique predictors of reading achievement, but not math achievement. This study suggests that the relationship between optimism and reading achievement is not explained by the other measured variables. The findings have implications for how educators can leverage optimism to help Latinx students in their reading achievement, an area where they often struggle (Hemphill & Vanneman, 2011).