Pendleton's death in January 2013 sparked a national movement against gun violence. Saturday's third annual "Wear Orange for Peace" event at the Harold Washington Playlot Park honored the teenager.
The movement uses the color orange, which protects hunters, as a symbol to honor the lives of those affected by gun violence in Chicago and across the nation.
"We need someone to understand we're human ... This is not something that should be ok," said Nza-Ari Khepra, the event co-founder.
Pendleton's friends started Project Orange Tree after she was gunned down near her South Side home.
"We don't understand it. But ... we deal with it and you've got to move forward," said Nate Pendleton, Hadiya's father.
"The whole Project Orange movement is supposed to be a safe space for everyone," said Cleo Pendleton, Hadiya's mother.
Hadiya Pendleton's parents were joined Saturday by former Arnie Duncan, former U.S. Secretary of Education and former CEO of Chicago Public Schools, and Cook County State's Attorney Kim Foxx, who talked about her office's gun crimes unit.
"We're building stronger cases and longer cases. We're really actively going after those are trafficking in guns," Foxx said.
Shari Springer, whose 20-year-old daughter Samantha was shot two years ago outside her home, attended the Project Orange event for the first time.
"I just wanted to be with everybody who's going through the same thing I'm going through," Springer said.
For Danetria Hudson, who was with her friend Hadiya when she died, there is one message: "Tomorrow is never promised. I just want people to realize hat the more you start talking to people and the more you start realizing what is going on, the better the solution will be."