North of Diliman lies the Commonwealth area, so-named because of Commonwealth Avenue (R-7) (formerly called Don Mariano Marcos Avenue) which runs through its center. This is primarily a middle-class residential area home to many subdivisions (residential associations) such as Don Jose Heights, Ideal Subdivision, Jordan Park Homes, Doña Carmen Subdivision, Filinvest's 1 and 2 and other subdivisions. Commonwealth area has one of the largest barangays in the Philippines as it plays host to one of the largest squatters' communities in the country. The population is so big as it is equivalent to a single highly-urbanized city. These include the areas of Batasan Hills (formerly called Constitution Hills), and within the proposed National Government Center.

Commonwealth Avenue is the widest road in the Philippines, where in some parts can stretch to as much as 16 lanes across.

At the heart of Commonwealth is the Batasang Pambansa (literally, National Lawmaking Center), which is where the country's House of Representatives holds its sessions. Many congressmen stay in houses in the surrounding subdivisions. This is also the location of Sandiganbayan and the main offices of Civil Service Commission, Commission on Audit and Department of Social Welfare and Development.

South of Commonwealth and east of Diliman is Balara. The area of Balara along Tandang Sora Avenue is relatively poor, while the outlying areas contain some of the richest subdivisions in the city. Capitol Hills Subdivision, Ayala Heights, and Ayala Hillside Estates are affluent communities. Adjacent to Ayala Heights and Ayala Hillside Estates is the Capitol Hills Golf and Country Club, a popular golf course.

The Polytechnic University of the Philippines has an extension campus in Commonwealth area, serving the parts of northern Metropolitan Manila.