Two decades ago, experimental social psychologists became interested in the emotion of passionate love, the desire for union with another. Recently, sex researchers have begun to focus on sexual desire, the desire for sexual union with another, or the loss thereof. In this paper we review what experimental social psychologists have learned about the nature of passionate love in the last two decades and contrast their view of passion with that of sex researchers, especially with regard to the role that anxiety plays in the intensification/dimunution of passion. Finally, we suggest that researchers might profitably use the same paradigm to study these heretofore separate phenomena.