"This is a heartfelt thank-you from Ed Rendell to his supporters," said Michelle Singer, Rendell's campaign finance director. "He wanted this to be his big thank-you to everyone who has stood by him over the years."
Included on the invitation list: Mayor Nutter and former Mayor John F. Street, and donors large and small.
Event organizers say that even people who contributed as little $5 to Rendell (including when he was mayor of Philadelphia) - or simply volunteered their time - will receive an invitation.
And the invite, which features a picture of a beach chair, beach umbrella, and beach ball, recommends casual attire.
The governor - who is not expected to be sporting beach wear - will make a short speech at some point during the concert.
Singer could not say exactly how many invitations were being mailed and e-mailed, or how much it would end up costing the campaign committee.
But event organizers say the Electric Factory was chosen, among other reasons, because it can accommodate several thousand people.
Some snacks will be free, but drinks will not.
And, as the invitation says, "due to fire marshal restrictions, first come, first served."
Contact staff writer Angela Couloumbis at 717-787-5934 or firstname.lastname@example.org.