Global Assessment of Functioning
Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
The Global Assessment of Functioning (GAF) is a numeric scale (0 through 100) used by mental health clinicians and doctors to rate the social, occupational and psychological functioning of adults. The scale is presented and described in the DSM-IV-TR on page 32. Children and adolescents under the age of 18 are evaluated on the Children’s Global Assessment Scale, or C-GAS.
Superior functioning in a wide range of activities, life's problems never seem to get out of hand, is sought out by others because of his or her many qualities. No symptoms.
81-90 Absent or minimal symptoms, good functioning in all areas, interested and involved in a wide range of activities, socially effective, generally satisfied with life, no more than everyday problems or concerns.
71-80 If symptoms are present they are transient and expectable reactions to psychosocial stresses; no more than slight impairment in social, occupational, or school functioning.
61-70 Some mild symptoms OR some difficulty in social, occupational, or school functioning, but generally functioning pretty well, has some meaningful interpersonal relationships.
51-60 Moderate symptoms OR any moderate difficulty in social, occupational, or school functioning.
41-50 Serious symptoms OR any serious impairment in social, occupational, or school functioning.
31-40 Some impairment in reality testing or communication OR major impairment in several areas, such as work or school, family relations, judgment, thinking, or mood.
21-30 Behavior is considerably influenced by delusions or hallucinations OR serious impairment in communications or judgment OR inability to function in all areas.
11-20 Some danger of hurting self or others OR occasionally fails to maintain minimal personal hygiene OR gross impairment in communication.
1-10 Persistent danger of severely hurting self or others OR persistent inability to maintain minimum personal hygiene OR serious suicidal act with clear expectation of death.
0 Not enough information available to provide GAF.
Use in litigation
Montalvo v. Barnhart, 2005 U.S. Dist. LEXIS 44133 (W.D.N.Y. 2005).
Montalvo attempts to substitute “overall level of functioning and carrying out activities of daily living” with “social, occupational, or school functioning." It is possible to see the possibility of some degree of overlap because "Social functioning" is arguably a subset of overall functioning and Activities of daily living. However, some have argued that equivalence is not clearly stated in DSM-IV-TR. Commissioner citing Wikipedia in a brief, SSAConnect (2007)