When you’re the largest library in the world and it comes time to take stock of your historical and administrative development, you don’t just write a book, you write an encyclopedia.

And so, more than 200 years after its 1800 founding, the Library of Congress, in conjunction with Bernan Press, did just that: This month it’s releasing its first ever one-volume “Encyclopedia of the Library of Congress: For Congress, the Nation & the World.”

The 569-page reference book includes hundreds of photographs, more than a dozen overview essays and nearly 80 shorter articles focusing on the different functions and activities of the Library and its divisions.

“For an institution, it’s unusual” to have an encyclopedia, said the book’s co-editor, John Cole, director of the Library of Congress’ Center for the Book. “We are a whole subject by ourselves.”

The book was a natural fit for Cole, who has published works on everything from the Library’s basic chronology to its art and architecture. He first got the idea for the book in the mid-1990s, when preparations for the Library’s 2000 bicentennial got under way.

“I realized the Library needed a large, scholarly history but in fact an encyclopedia might be more immediately useful and more doable,” he said.

Cole, whose 1971 Ph.D. dissertation explored the Library’s institutional development, took his idea to the International Encyclopedia Society, which helped him develop a proposal to present to the Library for official approval, which he received in 1995.

Then came the hard part: pulling together the necessary material to round out the tome.

To accomplish this, he teamed up with his co-editor, Jane Aikin, historian and National Endowment for the Humanities senior academic adviser (the two wrote more than half of the essays and articles in the encyclopedia). They then began contacting the various divisions for assistance in writing the pieces — a task that proved difficult at times.

“I kept giving them deadlines,” he recalled, with a laugh, adding that a team of more than 50 Library staffers contributed to the book. “I’d say to the Asian division, ‘Well, the Hispanic division’s article is in.’”

The project had to be put on hold twice: first in 1999, when Cole was unexpectedly made co-chairman of the Library’s bicentennial, and again when he was drafted to serve as program coordinator for the new National Book Festival, launched in 2001. As a result, some of the material already in had to be updated once he returned to the project.

Cole, a 30-year veteran of the Library, said that despite his familiarity with the institution, he still stumbled on a few little-known tidbits in the process of his research. For instance, he said, during World War II some of the Library’s top treasures — such as the Gutenberg Bible — were moved for safekeeping to Washington and Lee University, the University of Virginia and Ohio’s Denison University, among others. What’s more, Cole learned that not until 1975 did then-Librarian of Congress Daniel Boorstin discover an envelope containing the contents of former President Abraham Lincoln’s pockets the night of his assassination, including a handkerchief, two pairs of eyeglasses and a cufflink, sitting undisturbed in his office’s wall safe. “I have no idea why [his predecessors] didn’t open it, but they didn’t,” Cole said, noting that the envelope had remained unopened for more than 30 years.

Among the useful resources compiled for the first time in the book’s appendices, Cole said, is a comprehensive list of the Library’s legislative appropriations from 1800 to 2004, as well as the first table ever created of the chairmen of the Congressional Committees on the Library from 1805 to 2004, researched by the Senate Historical Office.

At $125 a pop, the book, which will be available in the Library’s gift shop, isn’t likely to appeal to the tourist crowd — a point Cole readily concedes. It was “deliberately done as a reference book for libraries,” he said.

As for future editions, that will depend on the publisher. “We are not committed to one yet,” Cole said, but “who knows what will happen.”

In the meantime, Cole would like to see parts of the book digitized for online dissemination, possibly on an LOC-sponsored Web site about its history. “I’m lobbying within the Library to create interest,” he said.

Cole will discuss the encyclopedia from 1 to 3 p.m. Friday in the James Madison Building’s Mumford Room. The event is free and open to the public. ADA accommodations must be made in advance by calling (202) 707-6362.