A two-step sample selection model is used to estimate household demand equations for fluid milk and cheese products incorporating national generic advertising. This approach allows us to disentangle the incidence of the advertising effect on the probability of purchase and changes in the level of consumption. Generic advertising for fluid milk had a predominantly intensive effect on athome fluid milk demand, implying that advertising was relatively more effective at increasing the consumption of current consumers. Conversely, the at-home cheese demand response to generic cheese advertising was almost exclusively extensive, with virtually the entire increase in quantity demanded due to an increase in the household’s probability of purchase.