Fay L. Young, 56, a writer and former school psychologist who was active in public action organizations, died of an aneurysm Thursday at Suburban Hospital in Bethesda.

She had been a national officer of the Gray Panthers, an organization advocating the rights of the elderly, for the last four years. She also had been active with he Pension Rights Center, a nonprofit public interest group seeking to influence national pension legislation.

Mrs. Young and her husband, Dr. Leo Young, were coauthors of "Everything You Should Know About Pension Plans," which was published in 1976. In a review of the work, The Washington Post said, "This book has an amibitious title but lives up to it."

Mrs. Young became interested in pension plans and legislation about the time her husband was elected chairman of the pensions committee of the Institute of Electrical and Electronics Engineers (IEEE), a professional organization, in 1975. Dr. Young is now the IEEE's president.

Mrs. Young wrote a column, "Questions and Answers on Pensions," for the "IEEE Professional News."

She had made her home in Bethesda since coming to the Washington area in 1973. She was a member of the Ohr Kodesh Congregation in Chevy Chase.

Mrs. Young was a native of England and graduated from Newcastle University with a degree in economics. She earned a master's degree in psychology at London University.

After coming to this country in November 1953, she worked as a psychologist in the public schools of Baltimore and Palo Alto, Calif.

In addition to her husband of 28 years, of Bethesda, her survivors include two sons, Philip and Joseph, both students at the University of California at Berkeley; a daughter, Sarah, of Bethesda; her mother, Sophie Merskey of Sunderland, England, and two brothers, Dr. Harold Merskey of London, Ontario, and Donald Merskey of London, England.