For the first time since the Advertising Council was founded in 1942, the organization — which directs and coordinates public service campaigns on behalf of Madison Avenue and the media industry — is introducing ads meant to tackle a social issue of concern to gays and lesbians.

The campaign, which is scheduled to be announced by the council in Washington on Wednesday, will seek to discourage bullying and harassment of teenagers who are gay, lesbian, bisexual or transgender.

The campaign, created pro bono by the New York office of Arnold Worldwide, urges an end to using derogatory language, particularly labeling anything deemed negative or unpleasant as “so gay.” That is underlined by the theme of the campaign: “When you say, ‘That’s so gay,’ do you realize what you say? Knock it off.”

There will be television and radio commercials, print and outdoor ads and a special Web site devoted to the campaign (thinkb4youspeak.com). Some spots feature celebrities, the young actress Hilary Duff and the comedian Wanda Sykes, delivering the message.

The campaign is on behalf of a nonprofit organization in New York called the Gay, Lesbian and Straight Education Network, or Glsen (pronounced glisten), which promotes tolerance among students. Glsen is spending about $2 million to develop and produce the campaign.

Read the full story from the New York Times.