This book considers the kinematics and dynamics of the flows of fluids exhibiting a yield stress. Continuum mechanics governing the fluid mechanics is described. Two chapters are dedicated to analytical solutions to several steady and unsteady flows of viscoplastic fluids, including flows with pressure-dependent rheological parameters. Perturbation methods, variational inequalities to solve fluid flow problems, and the use of energy methods are discussed. Numerical modeling using augmented Lagrangian, operator splitting, finite difference, and lattice Boltzmann methods are employed. The second edition provides new sections on flows of yield stress fluids with pressure-dependent rheological parameters, on flows with wall slip, and on deriving the fundamental equations for Boltzmann lattice materials. Furthermore new material on the lubrication approximation and applications of finite differences has been added.