The objective of this handbook is to ensure the safe and correct application of a residual insecticide to indoor surfaces on which vectors may rest. Indoor residual spraying is extensively used, especially for malaria and Chagas disease vector control. However, vector control programmes frequently lack well-trained field staff to apply the insecticides and to maintain the application equipment. With good skills and quality application equipment, hazards to human health and the environment, as well as financial losses, can be avoided. It can be used as a model to develop training materials in the countries.