Firms often conduct both product and process R&D. Consumer preferences typically play a vital role in determining these R&D choices. The economics literature, however, has mostly ignored the interrelationship between the R&D choices of firms and consumer preferences. Istudy product and process R&D from the perspective of their relationship with consumer preferences. In doing so, I find a novel distinction between the two kinds of R&D. This distinction can explain several empirical observations regarding firms' choices of the two, and can also potentially enable us to better empirically identify the two.