When purchasing high involvement consumer durables such as new cars, consumers are assumed to progress through the following stages: Problem or Need Recognition; External Search; Alternative Evaluation; Purchase or Choice; Outcomes or Postpurchase Evaluation (see, for example Bettman 1979; Engel, Blackwell and Miniard 1993; Howard 1989). Much car buying research effort is directed at the latter stages of this process: buyers' uses of various information sources, choice-making strategies, post-purchase satisfactions, etc. However, the main proposition of this paper is that the initial phases of the consumer decision process have a major effect on the subsequent stages. In particular, it is proposed that the problem recognition "event" and the consequent retrieval of product related decision constraints from memory, substantially influences the ensuing processes of external information search, evaluation of alternatives and consideration set formation. The results from a national sample of new car buyers suggest that the type (rather than the amount) of prior decision constraints, identified as either marketer-related or household-related, that are activated as a consequence of the problem recognition event, significantly affect the "path" customers might follow through the remainder of the purchase process. The findings have important implications for modifying the traditional view of the consumer decision process as an orderly sequence, and for marketers to develop appropriate intervention strategies based on how prior decision constraints affect new car buyers.