This book is the first of two volumes that update Oscar Kempthorne's groundbreaking 1952 classic of the same name and is concerned primarily with the philosophical basis for experimental design and a mathematical-statistical framework within which to discuss the subject. As the primary focus is on intervention studies, the authors begin with a thorough discussion of linear models. At the heart of the book is a series of error-control designs based on fundamental design principles such as randomization, blocking, the Latin square principle, the split-unit principle, and the notion of factorial treatment structure.