Overview
The local rental market has been especially difficult in recent years and seems to be worsening. You will need to put a great deal of energy into your housing search, be aggressive about your search, and be prepared to act quickly. Good apartment deals can be posted and taken before you get up in the morning. Where to move will depend on several factors including price, distance to Harvard Square, and accessibility of public transportation. Below are descriptions of several areas where GSAS students tend to live.

It is an advantage to search for housing on location during the summer months, when the market turns in favor of renters. Many people sign year-long leases in September but move away in June, leaving you the chance to find sublets with an option to extend the lease. This gives you a chance to live in the apartment and deal with the landlord and the commute without any obligation to stay more than a few months. If you like the place and build a good relationship with the landlord, you can try to stay for the coming year. You might also consider starting a lease in June, so you won't have to sublet.

Cambridge
Many GSAS students live here, though generally it's more expensive than its neighbors further from Harvard Square. Cambridge is divided into several real estate enclaves: Harvard Square, Inman Square, Central Square, Porter Square, Cambridgeport, and North Cambridge. The Harvard Sq. area covers roughly Massachusetts Avenue ("Mass. Ave") from Sacramento to Hancock Streets, and from the Charles River to the Cambridge-Somerville line. The Inman Sq. area extends northeastward from Central Sq. along Prospect Street, and due north along Mass. Ave to the borders of MIT and Kendall Square. The Cambridgeport area is located along the Charles River from Western Ave. to Mass. Ave./MIT. The North Cambridge area runs northeastward from Porter Sq. along Mass. Ave.

Somerville
The second largest concentration of GSAS students is found in Somerville. Rents there are significantly lower than in Cambridge. Students tend to reside in three general areas: along the Cambridge-Somerville line (Beacon St.); in the vicinity of Porter Square; and around Davis Square. The Cambridge-Somerville line area is generally within walking distance (10-20 minutes by foot) to Harvard Sq. Porter Sq. is one stop away from Harvard Square on the Red Line of the T in addition to being a well-bused area within walking distance from Harvard Sq. It is therefore the most convenient area of Somerville in terms of public transportation. Davis Sq. is farther away, but still accessible via the Red Line and busses.

Watertown
Watertown borders Cambridge to the West. Rents in Watertown are also significantly lower, and it is easily accessible via #71 bus.

Greater Boston
Boston itself lies just across the Charles River from Cambridge and is easily accessible via bus, T, on foot, or by bicycle. Rents in the immediate areas of Boston, such as Back Bay, South End, Beacon Hill and the Fenway, are often higher than in Cambridge, but good deals can be found in Allston-Brighton. GSAS Students in the Program in Medical Sciences (DMS) often choose to live in nearby Brookline Village, Jamaica Plain (JP), Coolidge Corner, or Fenway. Coolidge Corner and JP tend to have lower rents. The Roxbury area offers lower rents as well, though is still considered by a few to be unsafe. Arlington is well-served by bus; despite its 978 area code, it's immediately north of Cambridge.