Dairy applications remain one of the largest applications of membrane technology in the world, with typical installations for both whey processing and cheese-making employing about 100 m2 of membrane area. This chapter considers the use of ultrafiltration in both whey processing and cheese-making, including the critical properties of the membranes required for these applications as well as the actual design and operation of the membrane modules/systems. The design of a membrane module for the batch concentration of whey involves the specification of the general module configuration, the detailed module geometry, and the specific flow conditions. The chapter examines the behavior of the tubular, spiral-wound, flat plate, and hollow fiber modules. Whey protein concentration remains a very attractive process in the production of hard cheeses, although this membrane ultrafiltration has been largely replaced by the J. L. Maubois, G. Mocquot, and L. Vassal process in the production of soft and semisoft cheeses.