Research suggests that special education teachers lack the pedagogical expertise and content knowledge needed to teach core mathematics standards and to develop the mathematical reasoning of fifth- and sixth-grade students with a mathematics learning disability (MLD). This study used a multiple-baseline design with randomization to examine the effects of a professional development (PD) package on eight special education teachers. The PD package incorporated Practice-Based Professional Development (PBPD) for teacher implementation of two learning strategies using the Self-Regulated Strategy Development (SRSD) framework. The primary dependent variable was the number of mathematical content questions teachers asked during instruction. The content questions were further categorized by question type (i.e., Level 1 were yes/no questions focused on mathematics content; Level 2 questions elicited one-word responses that focused on the mathematics content; and Level 3 questions elicited open-ended responses centered around four mathematical practices). Teachers were administered a mathematics content measure prebaseline and postintervention. Student participants (n = 31) were administered a distal fraction measure at prebaseline and postintervention and weekly progress monitoring probes for fraction accuracy, quality of mathematical reasoning, argumentative elements, and total words written. The overall visual, descriptive, and statistical results showed that after attending 2 days of PD, teachers' frequency of asking content questions statistically and meaningfully increased. However, their mathematical content knowledge showed no statistical increase from prebaseline to postintervention. The students demonstrated statistically significant gains on the distal learning measure. A minimum of three demonstrations of effect were found for fraction accuracy, argumentative elements, and total words written; however, the results on quality of mathematical reasoning were inconclusive. Both the teachers and students reported high social validity for teaching and learning the fraction intervention, respectively, and overall, the teachers implemented the intervention with fidelity. The findings from this study provide evidence for improving PD for special education teachers and for improving the fraction and writing outcomes for students with MLD. Limitation and future research are addressed. [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.]