Abstract: A comprehensive reptilian environment control system is provided that maintains a reptile enclosure within desired temperature and humidity ranges. The control system including the heat and humidity sources are provided in compact, convenient and safe modules which rest atop the enclosure. The user dials in the desired temperature and humidity settings and the control system automatically maintains the desired conditions. The system also provides simulated day and night lighting conditions. The system also provides simulated day and night temperature and humidity conditions by adjusting the temperature and humidity setpoints during the simulated night lighting conditions. A simple and reliable humidity source is also provided as part of the comprehensive environment control system.