We examine the effect of consumer and market factors on the trial probability of new consumer packaged goods. We distinguish between three sources of variation in consumer trial probability: (1) within new products, across consumers; (2) within new products, over time; and (3) across new products. Hypotheses are developed for the different variables concerning their likely effect on trial probability. The hypotheses are tested on weekly household-panel scanner data on the occurrence and timing of first purchases for 239 new consumer packaged goods over a 52-week period after introduction for a sample of over 3,500 consumers. We combine these household panel purchase data with consumer questionnaire data, retail scanner data, data on advertising expenditure, and expert ratings. We find support for most hypotheses. One of our main findings is that the effects of the consumers' personal makeup on the probability that they will try the new product are systematically moderated by elements of the marketing strategy associated with the new product and by category characteristics. The extensive data set provides a strong context for the generalizability of the findings. T he consumer purchase environment changes continuously. Each year, thousands of new products are introduced in the United States and elsewhere. Thus, decisions concerning whether to purchase a new product constitute an important component of consumer behavior. However, relatively little research has examined the adoption decision and the consumer and market factors influencing these individual consumer decisions (Moreau, Lehmann, and Mark-man 2001). Van den Bulte for constructive comments on earlier versions of this article, and Scott Neslin for providing the categories of ability to stockpile and impulse buying scores. The helpful suggestions of Dominique Hanssens, Valentina Melnyk, Vincent Nijs, Luk Warlop, and Michel Wedel are also much appreciated. chase, and sometimes it is interpreted more loosely to refer to the first few purchases. We focus on the decision concerning the first, or " trial, " purchase. This decision typically is associated with higher risk and lower product knowledge, while reactions by the social system are also less clear (Rog-ers 1995). Moreover, repeat purchases are contingent on trial purchase to have taken place, while trial is not contingent on repeat. The contribution of this study is twofold. First, although the consumer behavior literature recognizes both consumer and market factors as important drivers of the trial probability of new products (e.g., Gatignon and Robertson 1991), adoption research has typically focused either on consumer factors or on marketing variables (e.g., models like ASSESSOR). However, ignoring either type of factor can seriously bias one's conclusions about adoption processes (e.g., Van den Bulte and Lilien 2001). We study simultaneously consumer and market factors, including their main and interaction effects, on the trial probability of new CPGs. We examine these effects in a systematic fashion, developing and testing theory-based hypotheses. The focus in this study will be on understanding and explanation rather than on forecasting or normative prescription. Second, our data set on the occurrence and timing of first purchases for 239 new CPGs over a 52-week period after introduction for a sample of over 3,500 consumers allows for empirical generalizations regarding the factors underlying the consumer trial probability of new products, at least within the domain of CPGs. As Bass and Wind (1995, p.