Soil health is one of the most popular research agendas in current agriculture science. It has been addressed to some extent for centuries, but today we have the scientific tools to examine and quantify chemical, physical and biological aspects of soil. The link of soil health to human and animal health and the environment may seem obvious, but considerable debate still ensues both about ways to define soil health and how far particular soil management practices promote healthy soils. This chapter provides an overview of these debates. Better links to crop physiological outcomes and yield, and links to human and animal nutrition, are still required to better define soil health. Overall, the science of soil health is an exciting field of research required to ensure health and productive food and fiber systems that will benefit human and animal health, functioning ecosystems, and environmental integrity.