This book presents different thermodynamic approaches in the area of constitutive theory: thermodynamics of irreversible processes, rational thermodynamics, and extended thermodynamics. These different approaches are analyzed with respect to their presuppositions, as well as to their results, and each method is applied to several important examples. In many cases these examples are archetypes for numerous technologically important materials; i.e. complex materials having an internal structure. Some of the examples dealt with in this book are liquid crystals, colloid suspensions, ans fiber suspensions.  The book well serves students and researchers who have basic knowledge in continuum mechanics and thermodynamics. It provides a systematic overview of the vast field of thermodynamic constitutive theory, beginning from a historical perspective and concluding with outstanding questions in recent research.