Two-Body Dirac Equations for Relativistic Bound States of Quantum Field Theory

We review a little-known treatment of the relativistic two-body bound-state problem - that provided by Two-Body Dirac Equations obtained from constraint dynamics. We describe some of its more important results, its relation to older formulations and to quantum field theory. We list a number of features crucial for the success of such a formulation, many of which are missing from other methods; we show how the treatment provided by Two-Body Dirac Equations encompasses each of them.