Prior to this study, it was not known it was not known if and to what extent the adoption of the Positive Behavior Interventions and Supports (PBIS) predicts fifth-grade academic achievement in math and reading when controlling for baseline achievement in the previous grade for Native American students in rural elementary schools in Northeastern Arizona. The theoretical framework for this study included the theory of operant conditioning and cognitive behavioral theory. The original intent was to use a comparative design and two ANCOVAs to analyze 2018 and 2019 archival, student-level, math and reading assessment data from PBIS adopter and non-adopter schools. Due to the small available sample (N = 86 students), the comparative design was changed to a correlational-predictive design, and the comparative tests were replaced with two hierarchical regressions (with 2018 baseline scores as control predictors and PBIS adoption status as the main predictor of each 2019 subject assessment). The results showed that PBIS adoption was not a statistically significant predictor of student performance in on the 2019 fifth-grade math and reading assessments when controlling for the corresponding 2018 fourth-grade performance. However, the standardized beta coefficient for PBIS adoption in the complete model predicting fifth-grade math performance was found to be a close-to-significant negative predictor ([Beta] = -.125, t = -2.243, p = 0.028 > [alpha] = 0.025), which raised concerns about PBIS effectiveness in terms of math learning and justifies further research. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]