This chapter addresses the question whether and, if so, how personality matures across adulthood. To this end, we first clarify the terminology and integrate the different notions of positive personality development in an overarching framework. This framework proposes that there are two different types of positive personality development: adjustment and growth. Adjustment involves desirable change toward an individual's greater functionality in the face of developmental tasks and social norms, indexed by characteristics such as Agreeableness, Conscientiousness, and Emotional Stability. Growth involves transcending functionality for oneself and striving toward insight and improving the common good, indexed by personality characteristics such as Openness and personal growth. Adjustment and growth are associated with differences on many levels of psychological functioning. We review empirical findings that reveal different lifespan trajectories for adjustment and growth: whereas adjustment on average increases across most of the adult lifespan, growth tends to remain stable or even decrease after midlife. We delineate contextual and personal predictors and mechanisms that drive these two positive lifespan trajectories of personality. Finally, we discuss avenues for future research such as accounting for sociocultural factors and individuals' goals to better understand how adjustment and growth can be promoted.