Since the proposal, sixty years ago, of the direct dissociative recombination (DR) mechanism by Bates, there have been many important theoretical advances, especially within the past 30 years. Space limitations preclude the review of all significant theoretical contributions. Instead, I comment upon a few selected developments. Highlights of the early scattering theory of DR and of the powerful Multichannel Quantum Defect Theory (MQDT) are discussed. Enhancements to the latter approach have included the addition of second and all order K matrices, ion rotational motion, Rydberg states with excited cores and spin-orbit coupling between Rydberg states. Also discussed are DR by Born-Oppenheimer breakdown, angular product distributions in diatomic DR and oscillations in DR cross sections.