This book focuses on mechanical behavior, deformation, and fracture of materials, and how they play a critical role in the design of mechanical components under a variety of loading conditions. We have taken the approach of educating design engineers the key aspects of mechanical properties of material; in particular test methodologies to obtain important design parameters, and how they are taken into consideration during design for a variety of applications, such as static, fatigue and creep loading. The first part of the book presents an overview of mechanical design data, including the impact of statistical variation. The second section has a detailed discussion of the testing methods for obtaining this data. The third part discusses the role of micro- and macro-structure on mechanical behavior of materials. The emphasis will be on metals used for load bearing applications, with less emphasis on the other three material classes - ceramics, polymers and composites. The last section deals with the application of the above to various design situations.