Publisher Summary This chapter discusses rearing of insects. The goal of organized insect rearing is to provide reliable, affordable sources of high-quality insects for their many important purposes. It is now possible to rear literally thousands of insect species through multiple generations and many more for part of their life cycles. The greatest difficulty is to provide fresh host material or to develop a diet that is nutritionally complete and induces feeding, especially for predators or parasitoids. Precautions must be taken to start colonies with an adequate number of clean specimens and maintain them with very limited levels of mortality. These measures help to limit genetic bottlenecks caused by inbreeding, contamination with other species, and disease epizootics. As production levels and the number of species increase, rearing must be organized into systems with discrete operations or activities. These operations incorporate the rearing procedures necessary for each stage of the insect's life cycle plus acquisition and maintenance of supplies, equipment, and facilities. Facilities must be designed and constructed to contain and maintain the insects under specified conditions. Problems encountered in established insect rearing systems invariably are caused by inattention to procedural details or lack of environmental control. For the foreseeable future, advances in insect rearing will be focused primarily on culturing new species, maintaining existing colonies more efficiently, supporting advances in research and pest management, and increasing the use of insects in people's lives.