“I wanted to have a library that doubled as a dining room, where I could be surrounded by the books I love,” says best-selling author and historian Barbara Goldsmith, who hired interior designer Mica Ertegün to update and decorate her Park Avenueapartment.

In Washington, D.C.’s Georgetown neighborhood, Simon Jacobsen, a partner at Jacobsen Architecture, joined two 1863 row houses, creating aresidence for him and his family. A living room was transformed into a library with egg-cratelike shelving, chairs and tables by Le Corbusier and Eames, and a desk designed by the architect.

Designer Stephen Shadley and actress Diane Keaton, who has a passion for restoring old California homes, turned the double-height entrance hall of her Spanish Colonial Revival house in Beverly Hills into an entrance library, filling it with pots and other artifacts as well as books devoted to the visual arts. “The library sets the mood,” explains Shadley. “It’s a distillation of everything that goes on in the house.”

In a 17,500-square-foot penthouse overlooking the port of Monte Carlo, Martin Kemp, head designer atCandy & Candy, produced an opulent yet inviting library in a once-cavernous space. Kemp chose the vast numbers of antiquarian and modern books for the room, which he confessed was “no chore, because I love books.”

At a house she remodeled in California’s Carmel Valley, designer Sally Sirkin Lewis encircled the library with shelves, added French doors to bring in views of the lush landscape, and outfitted the space with Le Corbusier Grand Confort armchairs.

Architect David Ling renovated an Upper East Side apartment for a bibliophile neurosurgeon and incorporated a rare-book library—which Ling described as “the centerpiece of the design”—to the mix. Medical books, some dating to the 15th century, line the modern shelves. The sitting area features a Mies van der Rohe Barcelona table surrounded by a Le Corbusier love seat and sling-back chairs.

Among the improvements designer Friederike Kemp Biggs (with architect George W. Sweeney) made to her penthouse on Manhattan’s Upper East Side was adding a mahogany-paneled library. The favorite retreat of her husband, Jeremy, the room features an antique desk and a flat-screen TV concealed behind faux book bindings. There is an inscription on the ceiling adapted from a letter Thomas Jefferson wrote to John Adams in 1815: “I cannot live without my books.”

New York City decorator Thomas Jayne restored a 19th-century house in Philadelphia to its former glory. In the library, where French Empire chairs flank an English Regency table, the bookshelf also serves as a backdrop for art.

At a 1912 McKim, Mead & White building in Manhattan, Alexa Hampton installed custom bookcases that curve with the walls of the oval library. Gracing the space is a jewel-like metal frieze, while the curtains and tufted love seats, covered in powder-blue cotton velvet, add a gentle dose of color.

Architect Margaret Griffin, in collaboration with architect Elyse Grinstein, renovated a home on Los Angeles’s West Side, an area that has natural creeks and groves of indigenous trees. The star tree here is a 300-year-old sycamore that shades a small spring and lush slope in back. The snug library “started out with a full brick wall facing the tree,” explains the owner, but the brick was replaced by sheets of glass to bridge the room’s connection to the outdoors.

After Hurricane Katrina, designer Richard Keith Langham revisited and refreshed a Mississippi house he first decorated two decades ago. DealerKinsey Marable built the library’s varied book collection based on the owner’s interests; he also supplied the 19th-century ladder and antique globe.

For a house on Harbour Island in the Bahamas, Lea Ciavarra and Anne Marie Lubrano, of Lubrano Ciavarra Architects, utilized Bahamian colonial-era details and natural materials. The central gathering place is the soaring two-story library, a cube measuring 24 feet in all directions. As in most other portions of the house, the room is lined with dense, termite-resistant South American ipê wood.