Under Title XVI, a child under the age of 18 can be considered disabled by the Social Security Administration if they have a mental or physical health condition which is so severe that it causes a marked functional limitation. The condition must be expected to last at least 12 continuous months or result in death. The Social Security Administration maintains a Listing of Impairments which they use to identify mental or physical health conditions which are so severe the claimant is generally unable to perform substantial gainful activity. Childhood Listings (Part B) of the Social Security Administration's "Blue Book" has a section which provides medical criteria which can be used to evaluate the conditions of a child under the age of 18. This section is used when the Adult listings does not include enough information to evaluate the particular disease and how it may affect a child.