This chapter outlines cell culture processes in monoclonal antibody production. Cell culture process development starts with cell line generation and selection, followed by media and culture condition optimization in small‐scale systems, including 96‐well plate, shaker flasks, and bench‐scale bioreactors, for high throughput screening purposes. Once the process conditions are defined, the process is often transferred to the pilot scale to get scale‐up information and to produce toxicology materials and later to cGMP manufacturing for production of clinical material. As development of a commercial cell culture process for production of a biological product is completed at the laboratory and pilot scales, the commercialization process begins with process characterization, scale‐up, technology transfer, and validation for the manufacturing process. The strong demand of therapeutic antibody production, relatively modest titers, and reduction of cost of goods has resulted in a trend toward large‐scale manufacturing. Today, the largest biotech companies are using several hundred to 2,000 L scale bioreactors for early clinical production and 10,000‐25,000 L stirred tank bioreactors to produce commercial products.