The authors review literature that challenges the view that vasospasm involving large arteries is the exclusive cause of delayed ischemic neurological deficits (DINDs) following subarachnoid hemorrhage. They discuss alternative mechanisms and review the evidence supporting a potential role for thromboembolism. They conclude that vasospasm and thromboembolism play interrelated and additive roles in the development of DINDs, and that this interaction provides opportunities for novel therapeutic approaches.