The manual describes and is a guide to the user of Version II of the Integrated Air Pollution Control System (IAPCS-II), a computerized simulation model for estimating the costs and predicting the performance of sulfur dioxide, nitrogen oxides, and particulate matter control systems for coal-fired utility boilers. It gives the design bases of the modules comprising the model and the structure of the program itself, as well as the bases for a number of model enhancements available to the user. The model includes conventional and emrging technologies that effect pre-in situ, and post-combustion emission control. The model can accept any combination of the technology modules built into the system. Interactions are reflected in a material balance tabulation of the exit of each module. Alterations in the material balance are used to account for integrated performance and cost effects. The emission control technologies contained in IAPCS-II can be selected in either isolated or integrated configurations. IAPCS-II incorporates a number of enhancements to the design premises of the emission control modules, as well as the model's user access and versatility.