Toward a Theory of Lifespan Personality Trait Development

The lifespan development of personality traits has evolved from a niche topic to a core subject of psychological science. Looking back at 20 years of research, I review the personality development literature against three criteria for strong psychological theories. Overall, the field has come a long way toward refining our theoretical understanding of lifespan personality trait development. Major accomplishments include the establishment of evidence-based trait measures, the identification of robust patterns of trait stability and change, and the documentation of both environmental and genetic contributions to lifespan personality development. These insights put the field in a position to make transformative advances toward stronger and more precise theories. However, there are still several open questions. I discuss ideas to overcome existing obstacles to the development of strong lifespan personality theories and close with an overall evaluation of the theoretical status of the field.