Book excerpt: Plant resistance to insects. Types and classification of resistance. Biochemical and morphological bases of resistance. Genetic factors affecting expession and stability of resistance. Environmental factors influencing the magnitude and expression of resistance. Insect behavior and plant resistance. Insects and plant pathogens. The pathosystem concept. The problem of variable pests. The use of plant incect models. Resistant varieties in pest management systems. Germplasm resources and needs. Breeding systems for resistance breeding for resistance in specific crops. Breeding approches in alfalfa. Breeding approaches in cassava. Breeding cotton for resistance to insect pests. Breeding approaches in rice. Breeding sorghums resistant to insects. Breeding forest trees resistance to insects. Breeding approaches in wheat. Future opportunities and directions.