The Club offers overnight accommodations for members, sponsored guests of members, and members of Reciprocal Clubs.

All overnight rooms and suites have private bathrooms, cable television, and high-speed Internet access. Parking is also available for a nominal charge.

Members and guests may check in anytime after 3:00 pm and check out time is at 12:00 pm. Requests for early check-in or late check-out may be granted depending upon availability. Following your arrival, please inquire with one of the Front Desk staff. All cancellations must be submitted no later than 12:00 pm (EST) on the day of your reservation in order to avoid being charged in full.

To check availability and request a room reservation, please call 202-387-7783 or send an e-mail to [email protected].


The Mansion is the main building of the Cosmos Club and was built for the Townsend family in 1902. The ground floor has the main lobby, reception area, dining room, bar, and the Club Room.

The second floor houses the Warne Ballroom, the Library, and additional rooms for private events. The third floor contains the Billiards Room, Card Room, three meeting rooms, and six overnight rooms. The fourth floor houses five overnight rooms, one suite, and the Writers Room. The floors are connected by a small self-service elevator.


The Annex was built in 1952 to provide more sleeping rooms for members and guests. The rooms offer comfortable, affordable sleeping accommodations for members and guests traveling alone or with a partner.

Hillyer House

The Hillyer House, opened in 1998, once housed the French Military Mission. The building was completely renovated and connected to the main building by a glass-enclosed two-story bridge. On the first floor, one will find a very pleasant sitting room and a Business Center equipped with computers and a printer.

All overnight guests enjoy…
-Signature bathroom amenities
-Complimentary coffee
-Deluxe bathrobes
-High-speed Ethernet and Wi-Fi
-In-room security safe to store your valuables
-Same day laundry service: Laundry lists are in the desk drawer and bags are in the closet of your room. Articles to be cleaned should be left at the Front Desk by 8:30 a.m. Laundry charges will be billed to your account.
-Free use of facilities of the Club, including fitness room, dining facilities, bar, library, billiards room, and business center.

The Club’s fifty overnight rooms consist of three separate areas: Mansion, Annex, and Hillyer House. Click here to view room rates. The Cosmos Club is a smoke-free facility.