BACKGROUND: Attempted separation of craniopagus twins has continued to be associated with devastating results since the first partially successful separation with one surviving twin in 1952. To understand the factors that contribute to successful separation in the modern era of neuroimaging and modern surgical techniques, the authors reviewed and analyzed cases reported since 1995. METHODS: All reported cases of craniopagus twin separation attempts from 1995 to 2015 were identified using PubMed (n = 19). In addition, the Internet was searched for additional unreported separation attempts (n = 5). The peer-reviewed cases were used to build a categorical database containing information on each twin pair, including sex; date of birth; date of surgery; multiple- versus single-stage surgery; angular versus vertical conjoining; nature of shared cerebral venous system; and the presence of other comorbidities identified as cardiovascular, genitourinary, and craniofacial. The data were analyzed to find factors associated with successful separation (survival of both twins at postoperative day 30). RESULTS: Vertical craniopagus is associated with successful separation (p < 0.001). No statistical significance was attributed to the nature of the shared cerebral venous drainage or the other variables examined. Multiple-stage operations and surgery before 12 months of age are associated with a trend toward statistical significance for successful separation. CONCLUSIONS: The authors' analysis indicates that vertical craniopagus twins have the highest likelihood of successful separation. Additional factors possibly associated with successful separation include the nature of the shared sinus system, surgery at a young age, and the use of staged separations. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.