The production of recombinant proteins using the baculovirus expression vector system in large-scale agitated bioreactors is discussed in this chapter. Detailed methods of the key stages of a batch process, including host cell growth, virus stock amplification and quantification, bioreactor preparation and operation, the infection process, final harvesting, and primary separation steps for recovery of the product are presented. Furthermore, methods involved with online monitoring and bioreactor control, which have a significant impact on the overall success of the process, are provided, including advanced online monitoring of physiological parameters such as biovolume and respiration activity for batch and fed-batch insect cell cultures along with their role in operating high cell density cultures.