It began as a block party writ large: a chance for those whom most people called homosexuals to party publicly in a Center City neighborhood they considered theirs and celebrate the beginnings of that openness.

Now, a decade and a half later, the straight world has learned "homosexuals" are too diverse to label with one word. They call themselves gay, lesbian, bisexual, transgender and, often, just people.

And the weekend event once known as PrideFest has been formalized into Equality Forum, an international weeklong convention focusing on sexual minorities in society, government and business.

It begins today, this year honoring such diverse people as tennis great Martina Navratilova and Mayor Street and featuring panels on topics including black urban gay youths, the legal status of same-sex marriage, and the emerging gay-rights movements in such long-closeted countries as China.

Malcolm Lazin, the former developer and federal prosecutor who founded the Equality Forum and who is its full-time executive director, said the continuing evolution of the event was natural.

"When we started this in 1992, we were breaking totally new ground," Lazin said. "But we had a different vision and wanted to be part of what was a nascent civil-rights movement."

For an example of how far the movement has come, one need only look at this year's Distinguished Service award winner: John Street.

As City Council president a decade ago, Street had an icy relationship with the gay community because he opposed extending benefits to unmarried domestic partners of city workers.

The issue was hot enough that the gay community backed Republican Sam Katz against Street in his first run for mayor. Since then, Street has reached out to gay leaders and named several gay citizens to public office, including City Solicitor Romulo L. Diaz Jr.

On Saturday, Navratilova will be honored with the Equality Forum's 12th annual International Role Model Award at an International Equality Dinner. M-A-C Cosmetics will be given the fifth annual International Business Leadership Award.

Though the forum draws tens of thousands to Center City, Sunday's block-party aspect - known as SundayOUT - is arguably among the lesser parts of its agenda.

Throughout the week, issues panels will hold free sessions at such Center City venues as the Prince Music Theater, 1412 Chestnut St., and Temple University Center City, 1515 Market St.

The rest of the year Lazin and the Equality Forum have moved into other arenas. The group's Fortune 500 project, for example, has lobbied the largest U.S. public corporations to ban job discrimination based on sexual orientation.

Since the campaign began in 2003, 463 of the Fortune 500 have complied with the request, including all 27 in Pennsylvania and all 23 in New Jersey.

Equality Forum has also produced three well-regarded documentaries: Jim in Bold, about the impact of prejudice on youths with different sexual orientations; Gay Pioneers, about participants in a gay-rights protest at Independence Hall on July 4, 1965; and Saint of 9/11, about the Rev. Mychal Judge, chaplain of the New York City Fire Department, who died in the terrorist attacks.

The last two films and the commemoration in October of GLBT History Month are important, Lazin said, because they give straight and gay audiences a view of how sexual minorities have contributed to U.S. history.

That view has been invisible in the public schools, he said, and "it's remarkably important for this movement to know that it has a great history."

Contact staff writer Joseph A. Slobodzian at 215-854-2985 or jslobodzian@phillynews.com.