This study investigated how a self-regulated learning intervention, implemented within a personalized learning environment, affected students' self-regulation, self-efficacy, and academic achievement at a middle school. The personalized learning environment in this study was two self-paced units within middle school seventh grade math classrooms. The study included 12 difference classrooms across four different teachers. A quasi-experimental design was used in order to provide a self-regulated learning intervention to the participants by class. Dosage of the intervention varied as some classes received the intervention for eight weeks and some classes received the dosage for only the second four weeks. A matching design was used in order to ensure that approximately the same number of students were in each dosage group. Outcome measures for this study were effort regulation (ER), metacognitive self-regulation (MSR), self-efficacy, and IXL Real Time Diagnostic score. The ER, MSR, and self-efficacy scores were from the MSLQ subscales for the respective constructs. Outcome measures were taken at the beginning, in the middle, and at the end of the study. As this study utilized repeated measures, the nonindependence of individual responses within participants was accounted for by using mixed effects linear regression. The mixed effects models determined that the self-regulated intervention did not have an effect on self-regulation or academic outcomes, but did have a significant effect on student self-efficacy. Along with the self-regulated intervention having a significant effect on self-efficacy, there were also significant effects for time, and the interaction terms time x treatment and time x treatment x co-taught. [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.]