Decompressive craniectomy is a neurosurgical technique in which a portion of the skull is removed to reduce intracranial pressure. The rationale for this procedure is based on the Monro-Kellie Doctrine; expanding the physical space confining edematous brain tissue after traumatic brain injury will reduce intracranial pressure. There is significant debate over the efficacy of decompressive craniectomy despite its sound rationale and historical significance. Considerable variation in the employment of decompressive craniectomy, particularly for secondary brain injury, explains the inconsistent results and mixed opinions of this potentially valuable technique. One way to address these concerns is to establish a consistent methodology for performing decompressive craniectomies. The purpose of this paper is to begin accomplishing this goal and to emphasize the critical points of the hemicraniectomy and bicoronal (Kjellberg type) craniectomy.