Abstract In this paper the author reviews the broad general picture of developments in biological control in relation to the increasing opportunities presented for its employment in developing programmes of integrated pest control worldwide. Included are not only the classical examples of biological control of insects and mites and of weeds but such other areas as biological control of vertebrates, of plant diseases, and of dung accumulations, and as well the development of crop plant varieties resistant to plant disease. The review is developed as a means of illustrating that biological control offers real potential as a major manipulatable tactic for central use and maximization in a strategy of integrated control of pests in a great variety of situations — on land and in water, from the tropics to cold, temperate and sub-arctic regions, in forests and range and in cultivated crops and ornamental plantings. It is noted that the employment of these biological control tactics are often self-sufficient but they are not expected to broadly replace the use of chemical pesticides, for chemicals remain necessary in most crop situations and are still our most reliable immediate solution to such a problem. The two types of tactics are to be used together where necessary, with the chemicals being used only where really required and in ways to supplement the use of biological controls in the broad sense.