This text on phase transformations is for final year undergraduate and postgraduate students of metallurgy, materials science or engineering materials. It should also be useful for researchers working in industrial materials laboratories. The book is effectively in two parts: chapters 1-3 contain the background material necessary for understanding phase transformations: thermodynamics, kinetics, diffusion theory and the structure and properties of interfaces. Chapters 4-6 deal with specific transformations: solidification, diffusional transformations in solids and diffusionless transformations. Case studies of engineering alloys are included to provide a link between theory and practical reality.