This handbook was designed as a reference tool for forest geneticists, tree breeders and other tree improvement personnel, as well as a textbook for university courses and short-courses at the graduate level in quantitative genetics. The chapters focus on the decision points faced by quantitative geneticists and breeders in designing programs and analyzing data. Beginning with a justification for the use of quantitative genetics in decision making in tree improvement programs, the book continues with a brief presentation of fundamental principles, followed by discussions and evaluations of mating designs and field test designs, the use of best linear predictors to estimate breeding values, the use of computer programs in the analysis of variance for genetic information, the deployment of genetically improved sk for capturing gains, the use of economic models for program justification, and the development of seed transfer guidelines.