Pre-adolescent and adolescent engagement in regular physical activity (PA), more specifically moderate-to-vigorous physical activity (MVPA), is associated with improved educational performance. Similarly, children's engagement in moderate-to-vigorous physical activity has shown to improve cardiovascular fitness levels, which can provide long-term benefits such as increased cognitive control (Pindus et al., 2016). It is well known that children usually engage in substantial amounts of physical activity during the school day, however, evidence has suggested that youth PA dramatically declines during the summer months. Numerous PA-based summer programs have formed due to the increased attention from various sectors including public health, education, and faith/community-based organizations. More recently, cardiovascular fitness has shown to positively influence executive functioning in youth. The strong relationship between cardiovascular "or" aerobic fitness and enhanced cognition is abundantly evident (Chaddock et al., 2011; Erickson et al., 2019; Ludyga et al., 2020), however limited studies have examined the relationship between youth social-emotional competencies, MVPA and cognitive functioning during a youth development summer program. The first study in this three-study sequence explored the vast literature base surrounding youth PA, academic achievement, and cognition by critically reviewing evidence solely produced by systematic-reviews and meta-analyses around this important topic. Results suggested extensive heterogeneity among reviews and meta-analyses, however most report small to moderately positive and null effects of chronic PA and MVPA on academic achievement and cognition. The second study assessed the relationship between youth's social-emotional competence, MVPA, and cognitive functioning (i.e., inhibitory control) while attempting to control for health-related fitness measures (i.e., aerobic fitness, BMI percentile), total accelerometer wear time and any acute PA effects. Participants were pre-adolescent and adolescent children aged 8-13, who attend a summer physical activity and wellness program (iPALS) partnered with a large public school district located in the Midwestern United States (US). Accumulated MVPA during the school day was be measured using the triaxial ActiGraph accelerometer wGT3X+, as well as System of Observing Fitness Instruction Time (SOFIT). Health-related fitness measures were assessed the first and last week of the program using FitnessGram modified PACER-2 test (15-m). Inhibition was be measured using the Eriksen Flanker task and academic achievement were determined using the Kauffman Test of Educational Achievement-3 (Brief). All cognitive and academic measures were also measured during the first and final week of programming. Lastly, Pearson (2020) Social Skills Inventory System -- Social Emotional Learning rating scale (SSIS-SEL) was administered to measure participants' perceived affective competence throughout a youth development summer program. Results indicated statistically significant effects of preadolescent's perceived SEL competence and MVPA, incongruent accuracy, congruent reaction time and academic achievement. In conclusion, youth enrolled in out-of-school PA opportunities framed around SEL might attain beneficial physical and psychosocial outcomes. Accordingly, the third study evaluated the effectiveness of Social Emotional Learning (SEL) to increase participant's MVPA through the implementation of the Teaching Personal and Social Responsibility (TPSR) teaching model. Participants were children aged 8-13 years old who attend the youth development summer program. Further, MVPA data accumulated during the program were objectively be measured with the triaxial ActiGraph accelerometer wGT3X+. The direct observation instrument, SOFIT supplemented capturing youth PA levels, in addition to providing insights into instructor behavior. The Tool for Assessing Responsibility-based Education (TARE) assisted with assessing TPSR implementation fidelity. Along with this observational data, participants completed the Personal and Social Responsibility Questionnaire (PSRQ) on the final day of the last week of iPALS programming. Findings suggest that TPSR had a small, but statistically significant relationship with underserved youth's PA engagement, more specifically sex differences between the amount of proportion of time spent in MVPA. [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.]