The rally began with a traditional Buddhist invocation. Jews and Christians also gave testimony.
"Too many are being murdered, too many are being bullied, too many have committed suicide," keynote speaker Bishop Yvette Flunder said during the rally.
The clergy want Congress to approve a bill that protects students from being bullied for any reason, including sexual orientation or gender identity.
"It's incredible to me that we don't have laws that protect kids so that they can get an education," says Rev. Phil Soucy, from Hope Lutheran Church in Annandale, Va.
Rev. Amanda Poppei preaches at the Washington Ethical Society in the Shepherd Park neighborhood.
"My faith is about the preciousness of every human life," she says.
Poppei says her fellow clergy will also ask Congress to repeal the Defense of Marriage Act and pass laws specifically protecting gays from discrimination.