Stability represents a fundamental concept in developmental theory and research. In this article we give an overview of recent work on personality traits and their stability in adulthood. First, we define personality traits and stability. Second, we present empirical evidence supporting change and stability of personality traits across the adult years with respect to conceptually and statistically different forms of stability. Third, we describe mechanisms and processes that enable trait stability. Finally, we discuss implications of trait stability for theory, research, and application.