This paper explores the interface between personality psychology and economics. We examine the predictive power of personality and the stability of personality traits over the life cycle. We develop simple analytical frameworks for interpreting the evidence in personality psychology and suggest promising avenues for future research. The paper proceeds as follows. Section I is the Introduction. Section II defines cognitive ability and personality traits and describes how these concepts are measured. Section III considers methodological issues that arise in interpreting the measurements. Section IV presents evidence by psychologists and economists on basic economic parameters. Section V examines the predictive power of the traits studied by personality psychologists who, in general, are a distinct body of scholars from the psychologists measuring economic preference parameters. Section VI examines the evidence on the evolution of preference parameters and personality traits over the life cycle. We summarize recent work in psychology that demonstrates stability in preference parameters across diverse settings. Section VII presents a framework for interpreting personality and economic parameters. Recent work in behavioral economics and psychology that seeks to integrate economics and psychology focuses almost exclusively on preference parameters. In contrast, we present a broader framework that includes constraints, skill acquisition, and learning as well as conventional preference parameters. Section VIII concludes by summarizing the paper and suggesting an agenda for future research. (Contains 5 figures, 2 tables and 114 footnotes.)