Tommy Harper is still haunted by the racism he endured as a Red Sox player and coach nearly a half-century ago, when he says epithets rained down on him from the stands at Fenway Park and from other players.

On Thursday, Harper joined other former Boston-area professional athletes and current executives of the Red Sox, Bruins, Celtics, Patriots, and Revolution to launch an antiracism initiative.

“Things have gotten better,’’ Harper said. “No sports club can be responsible for every fan who comes. But they are responsible for the way we respond’’ to racial incidents.

The “Take the Lead’’ initiative seeks to combat such incidents and hate speech at Fenway Park, Gillette Stadium, and TD Garden — and beyond. It also encourages fans to denounce racism in their own homes, businesses, and communities, Sox officials said.

“We, like many Americans, made the mistake of thinking that our region’s and country’s less-than-stellar pasts were firmly behind us, that 21st-century America was becoming a more inclusive nation committed to celebrating diversity. That is not the case,’’ said John Henry, the Sox’ principal owner, in a statement.

Henry also said that while Thursday’s unveiling was planned months ago, recent events — including controversy over whether professional football players should protest racial injustice by kneeling during the national anthem — have given the issue more urgency.

“Our sports teams, our athletes, are woven into the fabric of our society. For that reason, we cannot remain silent nor still,’’ said Henry, who also owns The Boston Globe.

Henry has been urging the renaming of Yawkey Way, citing the racist past of former team owner Tom Yawkey.

At the “Take the Lead’’ launch at Fenway Park Thursday, Sam Kennedy, the Sox’ president and chief executive, said the impetus for the initiative began after Baltimore Orioles outfielder Adam Jones was taunted with racial slurs during a May game at Fenway. A day later, a white man used a racial slur to describe a Kenyan woman singing the national anthem.

“The origins of this partnership . . . began in the wake of two appalling incidents involving hate speech right here at Fenway Park,’’ Kennedy said. “Those incidents reinforce the need for a more open and honest conversation around race.’’

Officials from the five teams began meeting in early June to discuss how to address racial incidents in their venues, Kennedy said. Thursday’s event featured a panel discussion that included Harper and team executives and the unveiling of a public service announcement video rejecting racism and discrimination. The video was shown during the Sox-Astros game, and will also be shown during games at TD Garden and Gillette Stadium.

‘‘If you hear something wrong, offensive, or hateful, speak up. Say something,’’ say the players in the video, including Dustin Pedroia, Devin McCourty, and Patrice Bergeron.

The effort was the first of a wider project that also includes a fellowship and career fair.

“It would be easier to talk about home runs and touchdown passes . . . and three-pointers, but we are here to talk about something critical,’’ said the Rev. Liz Walker, pastor of the Roxbury Presbyterian Church, at the event. “We are here to talk about race, a subject that stirs our passions . . . that confuses, angers, and frightens us. A topic that many of us would avoid altogether.’’

Mayor Martin J. Walsh, highlighting the city’s recent race dialogues, said that the national conversation on race has been ugly and that “voices in Washington’’ are not helping the matter.

“Our role here in Boston should be to take the lead,’’ said Walsh. “The conversation isn’t just about what has happened in Fenway Park, but what is happening in our city every day.’’

During the panel discussion, former star athletes recalled their experiences in Boston.

Cedric Maxwell, former Celtics player and current broadcaster, said he “hated’’ Boston when he first moved to the city. An African-American, he said he didn’t see many people who looked like him until someone took him to Roxbury and Dorchester.

“It was really different,’’ Maxwell said. “But the atmosphere in Boston has changed now. [And I’ve gone] from being a person who didn’t like it to now a person who considers this as my home. And I really like Boston now.’’

He also highlighted the fact that the Celtics have been a leader in diversifying their roster. The team, he said, had the first black player, the first black coach, and the first team to have five black starters.

Harper, who now serves as a Sox player development consultant, also said he didn’t like Boston or the Sox when he came to the city in 1972. He recalled that during his first week of spring training, he learned that representatives from a segregated Elks club in Winter Haven were handing out free guest passes to white players only.

“Right from that point, I knew I could never be part of Red Sox Nation,’’ said Harper, recounting a story he told the Globe in 2014.

When he spoke up about the Elks, he said, he was eventually fired, but later rehired.

Harper said the racial climate is much better now because the current leadership is confronting such issues, rather than ignoring them.

Officials from several teams also spoke at the event.

David Hoffman, the Celtics’ senior director of community development, said theteam is tackling social justice and race issues by having players use real-life scenarios to engage young people.

“As we have these conversations in our locker room, we learn to embrace the uncomfortable,’’ said Hoffman. “People who hear things or see things oftentimes don’t know what to do.’’

Josh Kraft, president of the New England Patriots Charitable Foundation, said that while the racial climate has improved over the years, it will take everyone working together to address systemic problems such as “closing the achievement gap and getting everybody on an equal playing field.’’

Charlie Jacobs, the Bruins chief executive, highlighted the fact that the Bruins integrated before the Red Sox. In 1958, Jacobs said,the Bruins acquired Willie O’Ree — the first person of color in the National Hockey League. O’Ree was out of town and did not attend Thursday’s event. Currently, the Bruins have one black player.

Jacobs said the team recently donated 4,000 sets of hockey equipment to youths around the state. “Hockey is for everyone,’’ he said. “Our message is, everyone should feel at home.’’

John R. Ellement can be reached at ellement@ globe.com. Follow him on Twitter @JREbosglobe.