Between 2013 and 2014, 25.2% of 10th grade algebra students who worked with 870,000 adult volunteers in after-school programs in the United States met their goals of improved math proficiency scores. A gap exists involving volunteer training strategies for after-school programs that are effective in improving math proficiency of 10th grade math students. The purpose of this study was to explore what seven experts in the Atlantic Coastal Region of the United States believe are optimal practices for training volunteers in after-school settings. A modified Delphi process evolved towards consensus in three iterative rounds. Goffman's framing communication theory was the foundation to support the findings of the panelists. The research question that guided this study was: What math instructional strategies can leaders and trainers in low socioeconomic status (SES) communities use to enhance the support of volunteers who work in after-school settings with 10th grade students? Through purposive sampling, experts were selected based on their understanding of concepts related to math instruction and at least 10 years' experience working with the appropriate volunteers. Data analysis included extracting themes in each round and using these in subsequent rounds, while testing for and, ultimately, reaching consensus. Results involve 10 strategies for altering leaders' viewpoint regarding communication and collaboration between volunteers and trainers, building trust between volunteers and students, understanding needs of SES students, and teaching pedagogy using real-world examples. Organizational leaders and human service staff may gain key volunteer training strategies to develop robust after-school training programs. If adopted, strategies may transform contributions of volunteers to 10th grade math student learning and the employment trajectory of low SES high school students. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]