This paper presents a general theory of an elastic-plastic continuum, emphasizing the use of thermodynamic equations. The authors, A. E. Green and P. M. Naghi, build upon previous work in the field, particularly the contributions of Tresca, Saint-Venant, and Levy in the late 19th century, and later developments by Prandtl, Reuss, von Mises, and others in Germany during the 1920s and 1930s. The theory is described as a "rate-type" theory, distinguishing it from functional theories, and it does not restrict itself to small strains or isotropic materials. The paper discusses the historical context, the limitations of existing theories, and the need for a unified approach that links mechanical and thermodynamic considerations. It outlines the basic kinematical, dynamical, and thermodynamic equations for any continuum and presents the main results from the theory of large deformation of an elastic body. The constitutive equations are constructed using a geometrical formalism, referring to stress and temperature in a 7-dimensional space. The paper also highlights recent contributions by Drucker, Koiter, and Naghi, which have attempted to clarify the issues in the theory of elastic-plastic continua.This paper presents a general theory of an elastic-plastic continuum, emphasizing the use of thermodynamic equations. The authors, A. E. Green and P. M. Naghi, build upon previous work in the field, particularly the contributions of Tresca, Saint-Venant, and Levy in the late 19th century, and later developments by Prandtl, Reuss, von Mises, and others in Germany during the 1920s and 1930s. The theory is described as a "rate-type" theory, distinguishing it from functional theories, and it does not restrict itself to small strains or isotropic materials. The paper discusses the historical context, the limitations of existing theories, and the need for a unified approach that links mechanical and thermodynamic considerations. It outlines the basic kinematical, dynamical, and thermodynamic equations for any continuum and presents the main results from the theory of large deformation of an elastic body. The constitutive equations are constructed using a geometrical formalism, referring to stress and temperature in a 7-dimensional space. The paper also highlights recent contributions by Drucker, Koiter, and Naghi, which have attempted to clarify the issues in the theory of elastic-plastic continua.