The goal of this chapter is to summarize the main computational methods used in computer simulation and design of chemical processes that can be used to identify and analyze opportunities in pollution prevention and control. The material covered is by no means exhaustive. Therefore, the reader is encouraged to review the references for more specific details. The philosophy behind pollution prevention involves finding technological pathways and operations to make products in such way that the environmental impact of the process is minimum. We can see that such a framework or approach will necessarily create design and analysis of different alternatives. The total number of alternatives will depend on the type of application and objectives to be accomplished and can vary from a few to hundreds. The evaluation of the different alternatives can be greatly accelerated by the use of appropriate computational tools or procedures.