The New York Public Library is planning to transform itself, merging the administration of the branch and research libraries and making what the library’s president, Paul LeClerc, called “very large investments” in its digital resources and online presence.

The merger had been planned for some time but was accelerated when the director of the branch libraries, Susan Kent, retired in May. David Ferriero, whose previous title was the Andrew W. Mellon Director of the Research Libraries, will now be the Andrew W. Mellon Director of the New York Public Library.

To lead its digital efforts, the library recently hired Joshua Greenberg, a 30-year-old who holds a doctorate in science and technology studies from Cornell University , and is a self-described “humanist” whose experience as a historian gives him a close understanding of how technology can aid research.

The momentum toward what Mr. LeClerc called “a one-library concept” has been building since Ms. Kent and Mr. Ferriero arrived three years ago. “Both came in without any baggage about the historic separation” between the two systems, Mr. LeClerc said.

Mr. Ferriero, in fact, was surprised by the size of the divide. He likes to tell a story about how, on his first day on the job, he crossed Fifth Avenue to the Mid-Manhattan Library, got a library card, and borrowed a book. “Within a couple of hours, everyone knew that I had been to a branch,” he said. “Two days later, I got an e-mail from the director of the library at UCLA saying he’d heard I had been to a branch.”

Early on, Mr. Ferriero and Ms. Kent also noticed the considerable overlap between their operations. The most obvious area of duplication was in the separate electronic catalogs, which go by the acronyms LEO and CATNYP. Patrons have to understand the distinction between the two, which Mr. Ferriero claimed he initially did not: “It took me about three weeks to discover that I was using the branch catalog,” he confessed. “It was very embarrassing!” Users may even have to look up a book twice, if it isn’t available in the first catalog checked.

So the first major transition in the new “one-library” era will be the merging of LEO and CATNYP. The library is currently considering bids from library automation vendors, and Mr. Ferriero said he expects the unified catalog to go live in mid-2008. The city has given $7.75 million to fund the purchase, and the Picower Foundation has given another $1.3 million.

In order to prepare for the larger transition, which will ultimately involve merging the cataloging and acquisition departments, and possibly reconfiguring the staff in other ways, the library has been running a staff development program called the Leadership Academy, to encourage conversation and collaboration among members of various departments in both the research and branch libraries.

In the last decade, the library has made investments in digital technology, scanning almost 600,000 primary documents, including illuminated manuscripts, historical maps, and rare prints and photographs, for its Digital Gallery, and creating a large-scale digital collection connected to the Schomburg Center for Research in Black Culture, called “In Motion: The African-American Migration Experience.” The library has also made agreements with both Google and Microsoft to scan public-domain books from its collection. The Microsoft deal, which is the smaller, involves 50,000 books. Because the library is bound by a nondisclosure agreement, Mr. LeClerc would not specify the number of books being digitized under the Google deal, except to say it was “very big.”

The hiring of Mr. Greenberg means that what have been discrete, one-off projects will now become a core part of the library’s business. Mr. LeClerc said that the library is committed to making a major financial investment in putting content online. “These things don’t come cheaply,” he said. “We raised $7.5 million for the Digital Gallery. I raised $2.5 million for Schomburg’s digital library.”

One of his goals, Mr. Greenberg said, is for the library’s Web site and digital collections to reflect the democratization of knowledge that has occurred in the Internet era. Among the questions he’s considering is whether the library should begin collecting and archiving Web logs.

As more and more culture exists in digital form, “if you don’t make the decision to capture it, it disappears,” he said. “And if 50 years from now somebody is trying to figure out what New York City was like in 2007, they’re not going to have the kind of material we have now about the 1950s.”

In the same spirit, Mr. Greenberg wants to give library users more of an opportunity to interact with the existing collections. Traditionally, he said, if a researcher comes across a trove of uncatalogued papers in a library’s collection and turns it into her dissertation, she then writes what is called a finding aid, a document that describes what the archive contains. It serves as a thank-you to the library. Digital technology means that kind of interaction — “the idea that we’re all in it together,” Mr. Greenberg said — could potentially be taken much further. He imagines a future in which a researcher looking at materials in a special collection would work simultaneously with the actual documents and their digital equivalents. The digital version might allow zooming in on or comparing sections of the documents, or looking at other scholars’ notes.

But computer screens will never, Mr. Greenberg emphasized, replace the experience of actually seeing and handling the physical materials, either for scholars or for the schoolchildren who visit the library. “I remember the first time I held a 200-year-old book in my hands,” he said. “It was an eyeopening experience. I want to make sure to preserve that.”

Mr. Greenberg also wants library staff members to be able to share more of their knowledge with the patrons. He is running an internal pilot program in which many of the staff are keeping blogs, about “everything from the internal processes of the library to very public things,” he said. “A woman in this building has been working up a blog about food and culinary resources at the library, which draws across a number of different materials.”

He is also working with the map department to figure out how the maps in the Digital Gallery can be enhanced, so that rather than being static images, as they are now, they can function dynamically and interactively, so that a user can link from a location on a map to images of that site or descriptions from historical travel guides, or jump between maps of the same area from different periods.

The library will receive its own copy of the material currently being digitized by Google and Microsoft; one thing Mr. Greenberg has to figure out is what the library should do with it. Putting it online is only the beginning. The big questions are: “What’s the user experience of all this material? How do we want people to use it?” Mr. Greenberg said. “There’s a lot of talk about remix or mashup culture. If we’ve got all this older public-domain stuff, how do we get it out in the world and encourage people to build new culture out of it?”

A few months ago, as part of its effort to think about its future in a changing informational landscape, the library commissioned a study of its business and its users from the consulting firm Booz Allen Hamilton, which had previously worked with the Library of Congress and the National Archives. One of the things the study revealed was the robustness of the branch libraries, where the advent of the Internet, far from decreasing attendance, has actually increased it, since people who don’t have a computer at home will often go to a library to use e-mail or do Web research.

What this means, Mr. LeClerc said, is that while the library enhances its online resources, it also needs to devote attention and resources to its physical buildings, particularly in the branch library system. The Bronx Library Center, for example, housed in a $50 million green building designed by Richard Dattner, opened in 2005 and has been a resounding success. Attendance this year is projected to be 820,000. Mr. LeClerc said the Bronx Library Center was one of the things he is proudest of accomplishing in his tenure, and that it has become a blueprint for the branch libraries of the future.

The library’s board of trustees, which will meet next in late September, has yet to work through all the implications of the Booz Allen study and the new “one-library” system. What is clear now is that the library is moving toward a nimbler, more democratic model, focused somewhat less on what have traditionally been the library’s prestigious real estate — the research libraries — and more on the institution’s online and local presence.