It happened when a limo took her to a local restaurant.
When Mayor Thomas entered the Keya Graves Restaurant on North 9th Street, there were cheers and tears.
She thought she was attending an awards ceremony for the police chief, but instead, Thomas was escorted to the prom she never attended when she was younger.
"It's wonderful," Thomas said.
Dashawn Jenifer helped organize the prom with the help of other Fresh Start staff and campers.
The program helps children and teens in Darby Borough get their lives on track, emotionally and academically.
"She came to the Fresh Start program. We were talking and she actually said she had never been to her prom so I said it would nice if we gave back to her," Jenifer said.
So today they did. Anthony Allen, her prom date, gave her a hug, along with Kenneth Swinton who runs the Fresh Start camp.
Yeadon mayor Rohan Hepkins gave her roses, remembering that
last week their neighboring boroughs were impacted by less joyful news of the shooting on the campus of Mercy Fitzgerald Hospital, which is located in both Darby and Yeadon.
"When that happened last Thursday, Mayor Thomas and I were the first public officials on the scene," Mayor Hepkins said. "But it's great to be able to celebrate something like this after such an arduous week."
"The mayor does everything for our children here in Darby Borough. She doesn't turn a child away from any of the other boroughs," prom organizer Leslie McGirth said.
And today Mayor Helen Thomas attended her very first prom, making the rounds, greeting everyone she saw, then dancing the afternoon away.