Community Mental Health Assistance Act of 1979 - Amends title XVIII (Medicare) of the Social Security Act to include among the services provided under such title: (1) outpatient services by community mental health centers for up to 25 visits per year; and (2) partial hospitalization services by a community mental health center for up to 60 visits per year. Stipulates that the 190 days of inpatient psychiatric hospital services to which an individual is entitled under title XVIII during a lifetime shall be reduced by one day for every three partial hospitalization visits to a community mental health center. Sets forth the conditions of and limitations on payments for community mental health center services, including criteria for utilization review plans of community mental health centers and transfer agreements between hospitals and community mental health centers. Amends the Railroad Retirement Act of 1974 to include among the benefits which may be provided under such Act partial hospitalization services and outpatient services furnished by a community mental health center.