Children's poor social-emotional functioning has been an increasing concern prior to and amidst the COVID-19 pandemic. Childhood and adolescence are critical stages of life where they acquire key cognitive and social-emotional skills that shape their future mental health. When a student's social-emotional health suffers, so do their relationships, academics, and physical health. The theory of improvement hypothesized that students' social-emotional health can be improved via fostering trusting relationships, boosting self-esteem, and promoting healthy role models and positive adult-child relationships. To address the problem of practice, the primary investigator implemented a social-emotional learning (SEL)-infused, 8-week physical activity after-school program with a strong mentor/role model component. The following inquiry questions guided this dissertation in practice project: 1) How does students' social-emotional health change after participating the after-school social-emotional learning-infused physical activity program? And 2) What are faculty, staff, and parent perceptions of the impact of a social-emotional learning-infused physical activity program on third grade students? Measures included time sample observations during the program of n=7 at-risk students with behavioral or emotional challenges, field notes compiled by the primary investigator throughout the program, and focus groups with key stakeholders (i.e., n=8 teachers, n=8 parents, and n=12 mentors) conducted post-program. The patterns in changes of student behavior over time were reported as case-study narratives for each observed student. Focus group transcripts and field notes were coded using content analysis v method and analyzed for key categories and themes. Overall, students' time sample data showed positive improvements in social-emotional health as well as on-task behavior. Three themes were identified in the qualitative data, including: 1) Growing and thriving together: benefits of the afterschool program 2) Trial and error: reflecting on what went well and didn't go well in the program and 3) Onward and upward: Fine tuning the program for the future. This program demonstrated initial success for improvements in 3rd grade children's social-emotional health. Implications for practice include improved training for all stakeholders in social-emotional learning, inclusion of mentorship, and additional administrative buy-in, including logistical support and funding. Future research can investigate the effect on mentor and student overall mental health and academic achievement. [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.]