There are two important methods of insect control, viz 1) biological method and 2) chemical method. In biological method, insects are controlled in three ways, viz, 1) by the use of predators and parasites of insect pests. 2) by using botanical pesticides such as neem, Datura, Ipomea in the form of leaf extracts, and 3) use of resistant varieties. Biological method is cheap and does not have any adverse effect on the ecosystem, through lesser effective than chemical method of insect control. The chemical method includes use of various chemical, insecticides. Use of insecticides has several disadvantages. It increases cost of cultivation, reduces population of predators and parasites of insect pests, leads to environmental pollution and development of pesticides resistant biotypes of insects. Thus genetic resistance is the cheapest and the best method of insect control in crop plants. Genetic resistance refers to the ability of some genotypes to give higher yields of good quality than susceptible varieties at the same initial level of insect attack under similar environmental conditions. Thus resistance is defined in relation to susceptible varieties. This chapter deals with breeding for resistance to insect pests and parasitic weeds.