Campaigning for five seats on the D.C. Board of Education and a rent control referendum in Tuesday's election has kicked into high gear, highlighted by a strong challenge to school board member Barbara Lett Simmons and a referendum debate laced with racial innuendoes.

Simmons and David Eaton, the two at-large school board members seeking reelection, are running in a field of five candidates, with the two top vote-getters the winners. Eaton, the senior minister at All Souls Church, is considered a shoo-in for one of the seats, while Simmons is struggling to retain the second seat in the face of a strong challenge from Phyllis Young, a U.S. Department of Transportation branch chief.

Young, who has made it clear she is going after Simmons' seat, told about 300 students at a Ballou High School forum that Simmons "spends more time running for City Council than she does in her capacity as a school board member."

"She's ineffective and she doesn't deserve to be on the board," Young said.

Simmons, who ran for City Council last year and has served on the board for 11 years, countered with a sharp verbal attack.

"You've heard from a candidate you've never seen before," Simmons said. "She has used nothing but vitriolic diatribe. People who use vitriolic diatribe complain and bitch about somebody else because they have nothing of their own to offer."

In addition to the at-large school board seats, voters will select representatives for seats in wards 2, 3 and 8.

Meanwhile, partisans in the referendum campaign staged dueling news conferences during the past few days -- each claiming the support of influential clergy and accusing the other of distorting the facts.

Supporters of the referendum, which seeks to eliminate key provisions of the city's newly revised rent control law, include a coalition of tenant groups and labor leaders, City Council Chairman David A. Clarke and four other council members. Opponents, including Mayor Marion Barry, City Council member John Ray (D-At Large) and a group of prominent local clergy, are closely allied with leaders of the real estate industry, who contributed more than $20,000 to the campaign against the measure.

Opponents of the referendum have pointed out that several leaders of the other side are white and live in wards 2 and 3. A few opponents, including former City Council member Douglas Moore, have argued that white proponents of the referendum were more interested in retaining stringent rent controls on housing for middle-class whites than in stimulating development of low-cost housing for poor blacks in other parts of the city.

Moore recently wrote an an article in the Washington Afro-American that suggested that two white referendum backers, Gottlieb Simon and Valerie Costelloe, live in areas that have discouraged the presence of lower-income blacks.

Broadening his attack to include Clarke, a leading supporter of the referendum on the City Council, Moore accused "Clarke and his surrogates" of working to preserve for themselves "the best benefits of rent control."

That broadside drew a blast from council member Polly Shackleton (D-Ward 3), who said she was "shocked and disgusted at the racist tactics being used by the opponents of the referendum." Black political leaders and clergy aligned with Clarke and Shackleton have denied that their side is controlled by whites.

Debate over the substance of the referendum has been clouded by disagreement among experts over the effects of changes introduced into the city's rent control program in April by the City Council.

Those changes, hotly disputed at the time, were aimed at loosening controls to provide incentives to builders and landlords to renovate and create housing. Adversaries in the campaign dispute whether the referendum, which would reinstate some restrictive controls, would help or hurt renters.

A vote in favor of the referendum would eliminate exemptions from controls for properties in these categories:

*Single-family homes owned by fewer than five persons. Under the new law, these are exempted from controls once they are vacated.

*Buildings that were at least 80 percent vacant as of April 30, 1985. These are exempted from controls on a case-by-case basis at the owner's request, provided that tenants are properly relocated.

*Buildings that are declared "distressed" properties. These can be decontrolled under a new city program in which landlords can receive tax breaks, loans and grants to restore them.

*All rental units vacated after April 29, 1989. These are exempted from controls as they become vacant, but only if the city's rental vacancy rate is 6 percent or more and if a rent subsidy program of up to $15 million is funded. The present vacancy rate is disputed, with referendum supporters saying it is already 6 percent and their opponents citing a rate of 2.4 percent.

The school board races got off to a quiet start, but in recent weeks the pace has picked up.

Ward 8 incumbent R. Calvin Lockridge, who is challenged by five candidates, faces a possible repeat of the 1981 election in which he won with 38 percent of the tally, beating out six contenders who split the remaining vote.

With $2,240, Lockridge has raised more money than any person vying to unseat him. Absalom Jordan and Virginia H. Howard, each of whom has raised more than $1,500 and has won support from community leaders, appear to pose the strongest challenges to Lockridge.

The other candidates in that race -- Frank Sewell, an unemployed apartment manager, William Lewis, a postal carrier, and Lin Covington, a D.C. school math teacher -- have joined Jordan and Howard in labeling Lockridge a "failure" and criticizing his confrontational style.

In what has been a quiet race in Ward 2, R. David Hall, school board president, is running for reelection against the Rev. Charles Briody, an adjunct professor at the University of the District of Columbia. Wanda Washburn is running uncontested for a second term from Ward 3.

In the at-large race, Young, a parent activist whose $7,500 campaign chest is the largest among all candidates this year, won 17,903 votes in the 1981 at-large school board race. She has been endorsed by Manuel Lopez, who placed third in the 1981 contest, as well as City Council member Nadine P. Winter (D-Ward 6) and school board member Bob Boyd of Ward 6.

Also contending for seats in the at-large race are Jacqueline B. Shillings, a registered nurse at D.C. General Hospital, and Benoit Brookens, a lawyer and former City Council candidate.