Blenda Gall Neil Thompson, 66, who trained volunteers and planned events at the Smithsonian Institution for more than 20 years, died April 28 at the Orchard Senior Living Community in Warsaw, Va., where she lived. She had dementia.

Mrs. Thompson began her service with the Smithsonian as a volunteer and shortly became a full-time employee. She was a scheduler and trainer for Smithsonian volunteers, and she taught newly recruited security guards the roles of the various museums, becoming known throughout the Smithsonian complexes.

Among her memories from her early years was a visit by Charles Lindbergh to see the Spirit of St. Louis one last time after he learned that he was dying of cancer. He had not seen the aircraft since donating it to the museum in the early 1930s, and he spent about a half-hour alone in the cockpit one evening after the hall was emptied of visitors.

Her desk was a roll-top, situated front and center in the Smithsonian Castle where she could assist volunteers. When Pope John Paul II came to Washington to celebrate Mass on the Mall in 1979, there were no facilities available where he could rest. Her desk was commandeered as the most convenient place.

Later in her career, Mrs. Thompson became an event planner, first at the Office of the Secretary of the Smithsonian, then at the National Museum of American History, where she combined her interests in cuisine, design and protocol to create receptions, dinners and exhibition openings. She particularly enjoyed planning a 1993 retirement dinner under the Star-Spangled Banner for Gen. Colin L. Powell, who was finishing his Army career as chairman of the Joint Chiefs of Staff. She retired in 1995.

Mrs. Thompson was born in Seward, Alaska. Her family moved to Arlington when her mother became a secretary for Edward Lewis "Bob" Bartlett, Alaska's congressional delegate and first senator.

Mrs. Thompson graduated from Wakefield High School in Arlington and was a 1956 Cherry Blossom Princess representing Alaska. She graduated from Stephens College in Columbia, Mo., in 1958 and worked for John F. Kennedy's presidential campaign in 1960. In 1963, she worked for the Trust Territories administration. She traveled to the Philippines and Okinawa with her first husband.

Her marriage to John D. Livsey ended in divorce.

Survivors include her husband of 19 years, George Thompson; a son from her first marriage, Matthew Livsey of Norfolk; two brothers, Douglas W. Smith of Falls Church and Warren R. "Russ" Neil of Long Valley, N.J.; and three grandchildren.