This chapter describes a suitable working process for a substitution task. When substitution is carried out or any other task is performed, it is useful to proceed according to a specific plan or a specific working process, so to speak. The purpose of the working process is to ensure that all aspects of the problem are always taken into consideration, so that the optimal solution may be achieved. The working process is developed so that it runs through various phases. The background for the recognition of the problem may be as diverse as accidents, symptoms, an irritating odor, publicity, or orders from the Danish Working Environment Service. Additional information may be obtained from the Danish Working Environment Service’s register of products. If the purpose of the working process, example, is to degrease a material, there are, among others, the following possibilities: organic solvents, bases, or water.