This article examines the role of behavioral routines in decision making. In order to induce routines, participants were confronted with recurrent route decisions in a computer-controlled trucking game, which allows for manipulation of routine acquisition and strength. During the ®nal round of the game, time pressure and novelty in task presentation were varied as between-factors. It was hypothesized that time pressure would increase the likelihood of routine maintenance and novelty would increase the likelihood of deviation. Besides individual choices, response latencies and self-reports were additionally assessed to measure the amount of deliberation during decision making. Results show that time pressure strongly increased the probability of routine maintenance, even though the situation indicated the inadequacy of the routine. In contrast, novelty in task presentation provoked routine deviation and increased deliberation, as evident from response latencies and self-reports. # 1998 John Wiley & Sons, Ltd.Most of the situations in which we are commonly involved oer multiple means for goal attainment. Sometimes the option set is so immense that one could not make use of each and every alternative during a lifetime. For example, there are more restaurants than you could ever visit, and more surgeons than you could ever consult. This variety of alternatives suggests a high probability for variations in behavior, although everyday experience shows that variability is far more pronounced between, rather than within individuals. Particularly in recurrent choice, behavior variability decreases in individuals if the preferred option is reinforced continuously (e.g. Hull, 1943). Thus, it is hardly surprising that research from dierent domains has accumulated evidence for past behavior to be a powerful predictor of future courses of action (e.g.