While personality is relatively stable over time, it is also subject to change across the entire lifespan. On a macro-analytical level, empirical research has identified patterns of normative and differential development that are affected by biological and environmental factors, specific life events, and social role investments. On a micro-analytical level, however, little is known about the underlying processes driving personality development. We provide an integrative state process model of personality development that incorporates and builds on previous process approaches to personality. It integrates this micro-analytical state perspective into the well-established macro-analytical understanding of personality trait development. Specifically, we distinguish three domains of individual differences in (the level of and contingencies between) state processes: (1) Goals and Strategies, (2) Actions and Experiences, and (3) Evaluations and Reflections. These process domains build a continuous sequence, with each domain guiding state processes in the next. Each process domain itself and their dependencies within the succession may be subject to change, thereby reflecting normative (in the case of shared development in state processes) and/or differential trait development (in the case of unique development in state processes). Well-established effects of environmental and biological structures, social roles, age, and life events on personality trait development can be explained by systematic links of these macro-level determinants to the outlined micro-level state processes. This integrative, process-based approach is thought to provide a conceptual basis for empirical research aiming at a comprehensive and fine-grained process understanding of personality development across the lifespan.