Book excerpt: General Concepts of Tree Improvement. Variation and Its Use. Provenance, Seed Source, and Exotics. Quantitative Aspects of Forest Tree Improvement. Selection in Natural Stands and Unimproved Plantations. Seed Production and Seed Orchards. Use of Tree Improvemente in Natural Forests and in Stand Improvement. Selection and Breeding for Resistance to Diseases, Insects, and Adverse Environments. Vegetative Propagation. Hybrids in Tree Improvement. Wood and Tree Improvement. Advanced Generations and Continued Improvement. Gain and Economics of Tree Improvement. The Genetic Base and Gene Conservation. Developing Tree Improvement Programs.