Sport development is an emerging discipline in sport management due in part to the popular, normative associations between sport and its beneficial outcomes. However, concerns on how sport is used and designed as well as the miscomprehension of the word development cloud sport's utilitarian prospectus. Although research has started to address these concerns in youth and adolescent forums, research on adults using sport for developmental purposes is widely ignored. With life expectancy growing, the pressure to sustain living quality in late adulthood has become almost unmanageable. Maintaining quality of life in late adulthood is difficult. Drawing from human development and aging literature, quality of life is still possible in light of the challenges presented by multiple developmental forces. Developmental trajectories are the products of net gains and losses over the life course and are influenced by transitional events and the ability in people to adapt to them. In addition, development is both cumulative and innovative, which affirms that people in later stages of life can still develop. In order to do this, gerontological and psychological research argue that resources are key in the achievement of positive outcomes. However, research understanding mechanisms that affect resources that produce positive gains is still in its infancy. Hence, I constructed a dissertation with two studies using a multi-method approach to ascertain the role and efficacy of sport participation on the transitional process that undergirds the developmental trajectory. The impetus for this approach was to examine the utility of sport as a developmental force adults could consider in improving their overall quality of life. Study 1 used a life-history, qualitative method that reveals sports' role as an influential resource provider during life event transitions across a person's life. Data show that sport was believed to aid in the adaptation process that provided distinct benefits that other activities or support structures could not match or replicate easily. Study 2 used structural equation modeling to specify the magnitude of sport's role on resources during a specific transitional event that most adults will experience: retirement from the workforce. Quantitative evidence from this study yields support that sport participation can positively impact resources and retirement well-being directly. Both studies supply substantiation for the argument that sport participation can act as a positive developmental force for adults by assisting with the recruitment of resources and acting as a resource provider which affords adaptation assistance in transitions. The combined results demonstrate how sport may be viewed as a developmental tool which has practical implications for sport development and managers wishing to design sport for this purpose. In addition, the common assumption that sport development programming should be geared exclusively toward youth and adolescents is dismissed. This dissertation provides theoretical and empirical justification for creating positive adult developmental programming in sport. / text