[Excerpt] An extensive theoretical literature has developed that investigates the role of promotions as a signal of worker ability. There have been no tests, however, of the empirical validity of this idea. In this paper we develop the theory in a manner that allows us to generate testable predictions, and then investigate the validity of these predictions using a longitudinal data set that contains detailed information concerning the internal-labor-market history of a medium-sized firm in the financial-services industry. Our results support the notion that signaling is both a statistically significant and economically significant factor in promotion decisions. The paper also contributes to the extensive literature on the role of education as a labor-market signal.