We are revising the criteria in the Listing of Impairments (the listings) that we use to evaluate musculoskeletal impairments in adults and children who claim Social Security or Supplemental Security Income (SSI) benefits based on disability under titles II and XVI of the Social Security Act (the Act). The revisions reflect advances in medical knowledge, treatment, and methods of evaluating musculoskeletal impairments. When the final rules become effective, we will apply them to new applications filed on or after the effective date of the rules and to other claims described in the preamble. Individuals who currently receive benefits will not lose eligibility as a result of these final rules. Also, although some individuals with musculoskeletal impairments will not meet the requirements of these final listings, they may still be found disabled at a later step in the sequential evaluation process based on their functional limitations.