Usually considered benign tumors, meningiomas can display aggressive behavior characterized by multiple recurrences and invasion of the brain, dura, and adjacent bone. The aggressive or malignant phenotype is difficult to characterize due to the broad spectrum of behaviors exhibited by meningiomas. Recent classification schemes based on features of anaplasia rather than histopathology have been used successfully to identify meningiomas that exhibit features of the aggressive phenotype. Some such tumors can be identified preoperatively by radiographic characteristics. Surgery is the cornerstone of treatment for all types of meningiomas. Conventional radiation therapy is beneficial for patients with recurrent (or incompletely resected) benign meningiomas and is recommended for those with aggressive and malignant meningiomas. Stereotactic radiation and interstitial brachytherapy are useful in some refractory or recurrent meningiomas. Traditional chemotherapeutic agents are not very effective against meningiomas, but hormonal manipulation is under study for patients with inoperable tumors or those who are medically unsuitable for surgery.