The coupled response of solid materials to multiple fields, such as deformation, heat, electricity, and magnetism, plays a crucial role in modern engineering applications, from soft robotics to energy storage. Advancing theoretical models and numerical implementations for these coupled behaviours in solids is a challenging and exciting frontier in mechanics. This textbook introduces some foundational coupled theories in solid mechanics by starting from fundamental principles of mechanics, thermodynamics, and electrodynamics, and specializing to model particular 'smart materials'. Numerous representative simulations are provided, demonstrating key coupled behaviours and engineering applications for each theory. The large deformation coupled theories discussed in this book have been numerically implemented in the open-source finite element program FEniCS, and representative simulations which illustrate key coupled behaviors are presented for each theory. The FEniCS codes for the representative simulations shown in this book are available online on the book's companion website: .Ideal for graduate students, researchers, and practicing engineers, Introduction to Coupled Theories in Solid Mechanics serves as both an introduction to the field and a foundational resource for building the coupled theories and simulation tools of the future.