Casein is the major protein component of cow’s milk and is extracted commercially for a wide range of applications. Before casein is precipitated from milk by acid, milk is commonly concentrated by ultrafiltration to increase throughput and partly recover lactose. The degree to which the milk can be concentrated is limited due to higher concentrations producing a tough rubbery curd that causes downstream processing difficulties, particularly when casein is washed to remove calcium, lactose, whey and other impurities. This thesis examines using milk protein concentrates, MPC70 and MPC85 retentates from ultrafiltration, to manufacture casein. MPC85 was used on a large scale process, and MPC70 was used on lab scale process. Lab scale casein production techniques were developed to produce a similar casein to process scale. Effects of dilution and pH were examined on casein properties and calcium and lactose removal. Diluting the retentates prior to acidification was effective at reducing the residual levels of calcium and lactose in the casein, and no increase in residual whey protein was found compared to conventional casein production. The optimal precipitation pH remained at 4.60, and the resulting casein was not found to have any reduction in its functional performance. Lowering precipitation pH increased casein losses due to fines being formed and difficulty in separating wash water from the curd. Use of milk retentate for casein manufacture allows greater recovery of lactose and may have positive implications for the economics of the process in reducing washing required to produce high quality casein.