From a criminological life-course and developmental perspective, military service acts as a positive life event for most individuals. For others, it can serve as a catalyst for maladaptive life-course outcomes, including criminal justice system involvement. However, despite the well-documented negative risks of military service on veteran life-course outcomes and the increased prevalence of veterans in the justice system, relatively little inquiry exists that investigates first-hand accounts of the life-course experiences of veterans enmeshed within the criminal justice system. This dissertation begins to fill this gap by exploring the life-course experiences of justice-involved veterans in three separate, yet interconnected ways: (1) trajectories of deviance across the life-course and the impact of military service on deviance (Chapter 2); (2) the relationships between military service, mental health, and negative life-course outcomes (Chapter 3); and (3) the daily experiences of justice-involved veterans, including who they spend time with, what they spend time doing, and how these factors impact emotion (Chapter 4). This work is one of the few to utilize qualitative inquiry to better understand the relationship between military service and trajectories of deviance for justice-involved veterans, and is the first to use ecological momentary assessment (EMA) methodology to examine the daily experiences of justice-involved veterans. Findings suggest that the role of military service as a turning point is nuanced, and for many the military directly impacted both deviance and mental health outcomes. Further, emotionality of these veterans is quite variant over time, while social togetherness and engagement in activity show to be impactful on emotional well-being. Overall, this dissertation expands the understanding of the role of military service in the life-course, and provides an in-depth look into the daily and life-course experiences of justice-involved veterans, ultimately giving voice to the veterans themselves to articulate their own experiences and needs.