Interventional neuroradiology has made tremendous advances in the 28 years since Lussenhop and Spence [75] first reported occlusion of a cerebral AVM by embolization with radiologic guidance. This progress is largely attributable to continuing advances in imaging techniques, catheters, and embolic technology, coupled with an improved understanding of the natural history and pathophysiology of neurovascular disorders. In this evolving subspecialty there is still some variability in the consistency of results. It is hoped that subspecialty training guidelines will improve the consistency of therapeutic outcomes.