WASHINGTON (AP) _ Adult leaders of a sexual abstinence campaign for teen-agers say their movement is growing, spreading to hundreds of thousands of teen-agers from Canada to Uganda.

''Even though this first began as a campaign within the United States and was intended for the young people in our country, other nations are taking an interest by the day,'' Richard Ross, spokesman for the group True Love Waits, said Friday.

''Tonight, 6,000 teen-agers in Uganda will be meeting in a kickoff True Love Waits rally. The very same thing is happening in Canada this evening,'' he said. ''To date, 150 nations are actively involved in organizing True Love Waits campaigns for their young people.''

Ross addressed reporters during a ''SuperConference on Youth Evangelism,'' sponsored by the Baptist Sunday School Board, which he heads, and Youth for Christ.

As he spoke, teens worked behind him on the National Mall, hammering in little stakes holding cards signed by youths pledging abstinence. Ross said they planned to plant 200,000 of the multicolored cards by day's end.

''We have the sense that we're riding on the crest of a wave,'' said Dave Scherrer, a spokesman for Youth for Christ. ''Young people are beginning to say they can live a different way.''

True Love Waits was born a little more than a year ago when 59 teens took vows of chastity until marriage at Ross's Tulip Grove Baptist Church in Nashville, Tenn.

Last month, True Love Waits displayed 100,000 pledge cards at a meeting of the Southern Baptist Convention in Orlando, Fla. Next month, the group will hold a youth evangelism conference in Anaheim, Calif. And organizers are looking ahead to an international rally in Buenos Aires, Argentina, next year.

Several teen-agers attending the conference Friday said they hope to set an example.

''We're here today to say, 'I'm going to be abstinent until marriage,''' said Monica McIntyre, 16, of Hyattsville, Md.

''We have zillions of kids out here that want to do it, too,'' she said. ''If we're here and they see us, this might help them reinforce their beliefs and make them want to sign a card, too.''

Cresin Smith, 18, of Temple Hills, Md., said his generation is caught in ''a war between the flesh an the spirit.''

''The majority says, Have sex, have sex. Well, I say to you ... don't be pressured by your peers. Instead, pressure your peers unto righteousness.''

Susan Fitzgerald, 19, who belongs to Tulip Grove Baptist Church, said she signed the pledge ''because that's what God wants me to do with my life.''

''One of my friends once told me there are two different types of girls: the type of girl that a guy wants to date and the type of girl that a guy wants to marry,'' she said. ''I want to be the type of girl a guy wants to marry because I believe that's what God wants for me.''