The authors bring together a diverse array of theoretical and empirical applications of quantitative genetics in this comprehensive work designed to be accessible to anyone with a rudimentary understanding of statistics and genetics. Central concepts are developed from first principles and are illustrated with examples. The book reflects the recent influx of quantitative-genetic thinking into evolutionary biology and includes the techniques for QTL (quantitative-trait loci) analysis. Although written as a general text in quantitative genetics, the book should also serve as a basic reference for the professional.