The purpose of this study was to explore how living outside of the passport country during the developmental years affected the experiences of adult Third Culture Kids (TCKs). Individual interviews were conducted with 15 adult TCKs who had lived at least one year outside of their passport country prior to age 18 and had returned to their passport country for at least one year. They were asked questions about how their experiences living outside of their passport country affected them. Data analyzed from the interviews generated 13 themes: (a) broader understanding of the world and the differences of people, (b) developing a support system of genuine relationships based on support and understanding, (c) development of an identity that integrates experiences and cultures, (d) feeling misunderstood, isolated, and different, (e) experience resulted in opportunities and skills sets that are not traditional in the passport country, (f) challenges of returning to the passport country, (g) internal struggles in relating to others and developing effective coping skills, (h) ability to negotiate change and a lack of fear of change, (i) difference in understanding of wealth and financial management, (j) view experience as positive and life-changing, (k) challenges in adjusting to a different culture, (l) variation in relationships with family, and (m) desire to travel and be in other places. These themes and their repeating ideas generated a grounded theory about the experiences of TCKs. This theory represents the relationships between the themes and the research questions. The theory consisted of six elements: (a) development of a global perspective, (b) affirmation of the complexity of relationships, (c) struggle to achieve cultural efficacy, (d) confirmation of the value of the experience, (e) challenge of acculturation, and (f) change as a source of achieving equilibrium. Findings from this study demonstrated that the experience of growing up outside of the passport country during the developmental years was perceived as a valuable and beneficial experience that significantly affected the participants. The results also identified challenges of the TCK experience and the influences these had in participants’ lives. Research and practice implications are presented. Results of this study may assist mental health professionals to understand the term TCK and the challenges with which they may present for treatment. / Department of Counseling Psychology and Guidance Services