A special survey of the extensive field of Constitutive Laws is given in 11 lectures, divided into three parts: Thermodynamics of Materials, Stochastic Processes and Material Behaviour, Constitutive Relations for Simple Fluids and Microphysics of Solids. The collection of lectures comprehends a novel survey of thermodynamical constitutive theories, and contributions to material theories with after-effects including experiments, stochastic constitutive laws, molecular dynamics for simulating material properties, electrodynamical constitutive properties, and thermodynamic and microphysical modelling of polymers. The selected lectures emphasize the microstructural aspect of constitutive laws, and this collection presents a new facet of constitutive laws.