Increasingly, scholars and journalists are suggesting that there is a trend toward greater magnitude in career transitions signified by the crossing of career boundaries (such as level, functional, organizational, industry and professional boundaries). To date, much of the quantitative empirical research suggests that organizational, relational and environmental factors influence career transition behavior. However, while we know that these external influences may cause an individual to transition, we know less about the process through which career transitions evolve, especially those of larger magnitude and how forces internal to the individual may help to explain variance above and beyond these external factors. In this dissertation, I use qualitative and quantitative methodologies to develop and refine a model of career transition focusing on career transition magnitude. Specifically, I use research from social identity, social networks and role exit theory to develop a model of career transition magnitude that posits career identity (the cognitive representation of the self derived from past career experiences, beliefs, values, attributes and motives that define the individual in terms of their career) and network characteristics (the pattern of interpersonal relationships) influence the magnitude of intended career transition, the career exit behaviors one engages in and the evaluation of career opportunities. Further, I use path analysis to find that career exit behaviors are influenced by the magnitude of the intended career transition as well as strong coworker ties and social and personal turbulence. Additionally, I find that the favorable evaluation of career transition opportunities is impacted by career identity centrality and organizational satisfaction. Finally, I find that the magnitude of the intended career transition is influenced by the favorable evaluation of transition opportunities, network career range, organizational satisfaction and social and personal turbulence. Theoretical and practical contributions are discussed.