||Research surrounding psychological capital (PsyCap) continues to expand and develop as scholars and organizational leaders look to the strengths of positive psychology and integrate them into the workplace. While previous research has underscored connections between PsyCap and various organizational outcomes, there remains little research on its actual development. This study used a mixed-methods design to determine the efficacy of 6-week worksite intervention designed to improve the PsyCap of its participants. There were 49 individuals who participated in the first phase of this study (n=32 assigned to the treatment group and n=17 to the control group) and, from that group, 13 were selected to participate in a postintervention interview. Using a pretest/posttest experimental design, the study showed that the intervention was efficacious in helping employees to develop greater PsyCap. It further provided rich qualitative insight into the perspective of individuals with high PsyCap and how it was successfully developed. This dissertation is presented in a three-article format. Chapters 2, 3, and 4 are intended for publication in organizational health literature. Chapter 1 provides an introduction to the dissertation and an overview of the study performed. Chapter 2 is a review article which analyzes the construct of PsyCap and demonstrates the precedence for this concept in organizational behavior. It also makes the argument that there is a timely window to move this research and discussion into the field of health promotion in an effort to help employees develop PsyCap and to facilitate a more productive workforce. Chapters 3 and 4 are companion articles which provide the findings from this mixed methods study evaluating a work-site intervention in determining its efficacy on influencing employee's psychological capital. It also explored PsyCap from a qualitative perspective in an effort to provide insights learned from individuals with high PsyCap as well as a better understanding of its development. Chapter 5 provides a summary of the study, recognizes several limitations, and offers suggestions and direction for future research in the development of PsyCap and the role of health education programs in developing work-site interventions.