In this paper, we examine the over-time behavior of brand loyalty for a large set of brands drawn from 21 consumer packaged goods categories. Using the brand-loyalty operationalization of Colombo and Morrison (1989), the following conclusions are obtained. First, little support is found for the often-heard contention that brand loyalty is gradually declining over time. Second, while the short-run variability around a brand's mean loyalty level is not negligible, no evidence is found that this variability has systematically increased over time, and it can be reduced considerably through a simple smoothing procedure. Finally, the brand-loyalty pattern for market-share leaders is found to be more stable than for other brands. The study findings were robust to variation in the time interval used to construct the switching matrices, and to different treatments of multiple purchases. (C) 1997 Elsevier Science B.V.