This book identifies the converging fundamental knowledge bases underpinning the field of 3D cell culture and moves it from art to science. It provides a meaning of three-dimensionality and how it can be assayed. It also provides the value proposition for 3D cell culture in the major application areas. For example, 3D cell cultures are increasingly being used in therapeutic drug discovery programs to screen compounds with promise. The author uses carefully chosen applications to complement incorporated principles.