How do hormones and growth factors regulate animal growth in the developing embryo and after injury? What processes at the molecular level determine the growth patterns of different tissues? In this diverse synthesis of recent research, the regulation of growth in response to environmental and genetic stimuli is discussed at the level of the animal, tissues and cells. Contrasts are drawn between regulation in fetal and adult tissues, and in different tissues such as the CNS, bone and muscle. Functional chapters focus on the molecular links between mechanical tension and muscle growth, for example, while other chapters review the roles of specific molecules such as hormones and growth factors. This state of the art review will be of significant interest to graduate students and research scientists in the fields of animal growth, endocrinology and cell biology.