Although many students experience math anxiety in school, the contexts in which it occurs are not well-understood. Increased understanding of the environmental situations that might elicit math anxiety is needed to better support students' math achievement. Using a within-subjects design, we examined differences in math anxiety and math performance across math task timing (i.e., overt timing vs. covert timing) and math task complexity (i.e., simple vs. complex problems) with 113 fourth- (n = 38) and fifth-grade (n = 75) students. ANCOVA results showed no significant differences in participant reporting of math anxiety between overt and covert timing conditions for both simple (p = .27) and complex problems (p = .42). However, participants reported higher levels of math anxiety when working on complex math tasks compared to working on simple math tasks (p = .01). Findings also showed that participants with medium to high baseline math anxiety were more likely to report higher levels of math anxiety when completing complex math problems under the covert timing condition, p = .02, η2 = 0.13. Implications for practice and future research are discussed.