I investigate the causes, consequences, and measurement of subjective well-being. Specifically, I focus on three interrelated questions about positive emotional experiences. First, I investigate the associations between personality traits and well-being, focusing mostly on the relation between extraversion and positive affect. I use the results of these studies to develop theories about the functions of emotions and the mechanisms underlying personality traits. Second, I investigate more general questions regarding the causes and consequences of positive emotional well-being. For example, I have examined the extent to which factors such as age, sex, marital status, and unemployment are associated with well-being, and the extent to which people can adapt to major life events. And finally, in all of these projects, I pay careful attention to measurement issues, focusing on the quality of the measures that we use to assess personality and well-being. I also am interested involved in issues about replicability and have been involved in efforts to promote replication and improve research practices in psychology and other sciences.