THE CITY is under pressure as never before due to rising property values in the Boston area--which translate into high rents and a frantic rate of development. By casting ballots tomorrow for City Council candidates who strongly support rent control and restrictions on development, Cambridge voters can make sure that when the city changes, it will be for the better.

The city rent control system, while far from perfect, does make 15,000 apartments affordable to people who otherwise might not be able to find housing in the Cambridge. Yet this system is under attack from freshman Councilor William H. Walsh and several other conservative Independents. Last term, five of the nine Councilors defended and tried to improve the existing rent control system, but this majority may be endangered in tomorrow's election. If it vanishes, so will protection for thousands of tenants.

Cambridge's unusual proportional representation system permits voters to support as many Council candidates as they like, in order of preference. We suggest you head your ballot with the names of the seven pro-rent control candidates, and that you give your #1 vote--which counts most--to incumbent Councilor David E. Sullivan.

The Cambridge Civic Association has endorsed five candidates who support its platform of clean government and progressive housing legislation--incumbents David E. Sullivan, Alice K. Wolf, Saundra M. Graham and Francis H. Duehay '55, as well as newcomer Jonathan S. Myers, former director of youth programs for the Cambridge Housing Authority.

Two Independent candidates also deserve your vote: Ed Cyr, a liberal activist with local roots, heads a advocacy group for city elders and has worked against hazardous waste disposal; he would bring experience and dedication to the Council.

Incumbent Councilor Alfred E. Vellucci's unique brand of populism includes crucial support for rent control--he provides the outgoing Council's fifth "swing" vote to protect the system. Vellucci, however, opposes the CCA candidates' effort to create a "linkage" program that would help alleviate the pressures of development by requiring largescale builders to add to the stock of affordable housing.

The person who deserves your #1 vote, though, is City Councilor David E. Sullivan, the Council's best spokesman for students' and tenants' interests. While studying at Harvard Law School, Sullivan got students the right to vote in Cambridge. Since his election in 1980, he has put his conscience and legal acumen to work developing innovative measures to strengthen rent control and preserve neighborhoods.

One of David E. Sullivan's strongest successes is a 1980 law that bars landlords from selling-off rent-controlled apartments as condominiums. When opponents challenged this law, he battled them all the way to the Supreme Court--and won.

And this year David E. Sullivan faces a threat from an opponent of rent control who has almost the same name: anti-rent control candidate David J. Sullivan. It would be a tragedy should the city lose the services of David E. due to the confusion this challenger could cause.

The city needs your help this year. Do vote.