The teaching and learning of mathematics are essential to building daily discipline and encouraging logical reasoning and mental rigor. Engaging in mathematics helps to provide an overall understanding of the world. Exposing students to use mathematics to identify relationships and patterns is the basis for engaging in carrying out daily tasks. The purpose of this qualitative study was to better understand how elementary school principals perceive the effectiveness of mathematics professional development (PD) on teachers' instructional practices. Utilizing the ZOOM virtual platform and an interview protocol that included 10 open-ended questions, elementary school principals shared their experiences with providing mathematics PD for their teachers and their follow-up for impact on classroom instruction. Results revealed that principals perceived mathematics PD to be planned in conjunction with the attending teachers and tailored to their needs. Principals offered considerations for facilitators of mathematics PD to be well-versed in the content area and provide cyclical instructional support. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]