Cerebral amyloid angiopathy is a disorder in which deposition of amyloid within the arterial media and adventitia leads to intracerebral hemorrhage. Diagnosis during life has been hampered by the requirement for post-mortem examination for definitive diagnosis. The Boston Criteria for the diagnosis of cerebral amyloid angiopathy-related hemorrhage were developed in 1995 and 1996 in order to meet the need for a standardized set of diagnostic criteria that can be applied to living patients. Using a combination of clinical, radiologic, and pathologic data, these criteria reliably differentiate lobar intracerebral hemorrhage into categories of possible, probable, or definite based on the likelihood of underlying cerebral amyloid angiopathy. These criteria will be crucial for disease classification for future clinical studies.