ROCKPORT — For the past 80 years, the Sandy Bay Historical Society has aided people in discovering the past.

Whether people are researching ancestors or just curious about the origins of their home, the society has been committed to sharing its collection of papers and documents with those taking the time to research the past.

To commemorate its anniversary, society volunteers have invited the public to attend their gala celebration Tuesday, Oct. 2, at 5:30 p.m. at the Emerson Inn.

After 80 years, the Sandy Bay Historical Society owns two historic buildings and a research library to be proud of.

Its holdings include a vast collection of papers on every facet of Rockport history, which are available to researchers on Mondays and otherwise by appointment.

Cynthia Peckham is curator of the society, which was founded by Dr. Marshall H. Saville in 1927. She has served in nearly every capacity for the group, including as its president in the 1980s. As curator, she has manned the society’s King Street museum between 2 and 5 p.m. every Monday for the past dozen years — and the Rockport-born resident wouldn’t have it any other way.

“For an all-volunteer organization, I think we’ve done pretty good,” Peckham said yesterday. “We’ve gradually been growing and have come a long way. We offer a (sense of security by preserving the past). That feeling is disappearing in today’s mobile society. For me, it’s a labor of love and we’re dedicated to rescuing as much primary source material as we can.”

That dedication toward preserving Rockport’s past started in 1925, when a group of residents began meeting with a goal to form a local historical society. By 1927, a charter for the Sandy Bay Historical Society had been obtained from the commonwealth.

From 1929 to 1957, the society operated out of the second floor of the Community House. In 1957, it purchased the 1832 Sewall-Scripture house at 40 King St.; the purchase was made possible by gifts and bequests from Rockport families.

The merger of the Village Improvement Society of Pigeon Cove and the Sandy Bay Historical Society in 1987 changed the official name of the organization to Sandy Bay Historical Society and Museums, Inc.

The Old Castle, a home acquired in the Village Improvement Society merger, has undergone repairs, beginning in 1988 and continuing today thanks to Community Preservation funding that was approved by the 2003 Town Meeting and again earlier this month at fall Town Meeting.

“An Oxford University dendrochronology team determined the timber used to (construct) the Old Castle had been cut in early spring 1711,” Peckham said. “Isn’t that amazing.”

Mary Sibbalds, 81, served as the Sandy Bay Historical Society’s president in the term preceding current President Susan Kielinen. Sibbalds, now a member of the organization’s board of directors, said her family goes back 11 or 12 generations in Rockport and that she began volunteering with the society after getting “hooked on genealogy research.”

“I enjoy helping people find the history of their family and homes,” said Sibbalds, who works with Peckham at the museum on Mondays. “We have a lot of good material here that’s not available anywhere else.”

By the 1930s, intensive drives to collect historic artifacts by gift or loan were a common event. Peckham estimates between 98 percent and 99 percent of the society’s collection was donated to it over the years. In 2005, the society was awarded a Documentary Heritage Grant from the Massachusetts Historical Records Advisory Board to create an inventory of Rockport’s historic documents and plan for their long-term care. Organizations participating in the Rockport Archives Project included the library, town clerk and selectmen’s offices and all five local churches.

Peckham said she is hopeful the society will very soon be able to publish a book of never-before-seen pictures taken by Rockport photographer Charles H. Cleaves. Before she died, Virginia Cleaves donated her father’s 1,800 glass-plate negative collection to the organization. The negatives, dating to as early as 1894, have already been scanned into a computer.

The photo collection is just one of several highlights Peckham will point out Tuesday during the 80th anniversary celebration. Dr. Saville’s great-grandson Randy Saville, a member of the board of directors, will present a champagne toast to the crowd as it enjoys hors d’oeuvres at the elegant Emerson Inn on Green Street.

Looking forward, Sibbalds said one of the society’s biggest goals is to attract more young volunteers.

People wishing to join the society or interested in attending Tuesday’s celebration should call the Sandy Bay Historical Society at 978-546-9533.