This monograph presents a new systematic approach to the continuum modelling of flow phenomena within materials endowed with a complex internal microstructure, such as polymers and liquid crystals. The approach taken in this text is novel in that it combines the principles of Hamiltonian mechanics with those of irreversible thermodynamics.The book begins by outlining the relevant physical prnciples and then goes on to the numerous applications. From their results the authors draw conclusions in relation to the available state-of-the-art knowledge of the corresponding subjects.