The residents allege the co-op's board of directors took too long to deal with their complaints about flyers which mocked, among other things, their physical disabilities.
Residents Debora Crew and her partner, Bill, say it's been a three-year fight to be heard at the tribunal, which continues Tuesday in Toronto.
"They're actually listening now," she said. "Before, we just felt totally ignored."
Resident Theresa Savoie says her nine-year-old son Zachary, who has cerebral palsy and uses a wheelchair, was targeted by the flyers.
"It's all for him," Savoie told CBC News. "He has to understand and see that society is cruel. But if he stands up for himself, and he sees me standing up for him ... then he's not going to let anyone push him around."
Residents testified that despite complaining to their co-op board, the posters kept appearing for months while growing more offensive.
Many residents who spoke to CBC News believe it was one of their own co-op board members who put up the posters, and that's why so little was done to help them. The board says these allegations have not been proven.
Kiel Ardal, the lawyer representing the co-op board, said there's no evidence anyone on the co-op board was involved.
There are more than 17,000 co-op units in Toronto and York Region. Instead of landlords, residents elect a volunteer board of directors.
Savoie said regardless of the outcome, she believes complaining about the flyers was the right decision.
"Any kind of discrimination should not be tolerated," she said. "And if we take a stand today, and the next couple of days, win or lose, we're still winners because we stood up for ourselves."
The tribunal hearing continues Tuesday when two police detectives who investigated the complaint are expected to testify.
Later this week, representatives from the co-op board will present their side of the case.