"Five years ago, I'd say we were approaching the tipping point for LGBT equality," Lazin said. "Today, I'd say we're beyond the tipping point."
Following a kickoff event Thursday evening and an after-work party Friday, the Equality Forum will host a series of panel discussions Saturday.
One of the panels will address how activists build GOP support for same-sex marriage. Another will focus on the intersections between religion and LGBT equality. Yet another will deal with LGBT issues in the workplace.
Each of the panels, held at the University of the Arts, is free and open to the public.
Among this year's featured panelists is the Rev. Frank Schaefer. A United Methodist minister from Lebanon County, Pa., Schaefer was defrocked last year for officiating at his son's gay wedding.
Schaefer, who is in the middle of an appeals process with the church, has been traveling to churches and college campuses nationally in recent months to spread his message of equality.
"I was silent for too long," Schaefer said. "I will never be silent again."
Schaefer, who has never attended an Equality Forum summit, said he was looking forward to the weekend's events.
"They're really attacking this issue on all fronts," he said. "It's not just the legislation side, but it's also the faith side and the social side."
In addition to Schaefer, a national legal panel on Saturday will feature Eric Kraeutler, a partner at Morgan, Lewis & Bockius. Kraeutler is serving as lead counsel in Palladino v. Corbett, a federal lawsuit filed in August 2013. The suit, filed on behalf of a same-sex couple legally married in Massachusetts, is seeking marriage recognition in Pennsylvania. Oral arguments in the case are scheduled for May.
"This is an important topic that's in the public eye," Kraeutler said. "I'm looking forward to hearing from some of the other panelists on their cases."
Saturday will wrap up with a dinner at the National Museum of American Jewish History, during which Pennsylvania Attorney General Kathleen G. Kane is to receive the Distinguished Equality Award.
Then, on Sunday, the summit, which is expected to draw more than 15,000, will come to a close with "SundayOUT! at the Piazza," a Northern Liberties festival with food, art and music. A $10 entrance fee is required for the festival.
"It's a fun way to end a historic weekend," Lazin said.
For information, go to: www.equalityforum.com.