Protesters across the five boroughs are blowing the whistle against the NYPD's Stop, Question and Frisk policy.
Members of the Stop Mass Incarceration Network gathered to arm the city's youth with whistles.
They're encouraging kids to speak up when they see a crime, either from cops or criminals.
Organizers say many of the city's officers unfairly target minorities and youth.
"All it has done is criminalized a whole population of young people for generations, and we need to put a stop to that," said one attendee.
"How are we to do homework help with a young person when they've just gone through an interaction with a police officer that has broken down their spirits with folks who they trust?" said David R. Shuffler, the director of Youth Ministries for Peace and Justice. "It's a real challenge in our neighborhood."
Mayor Michael Bloomberg and Police Commissioner Ray Kelly have defended the police tactic, saying it gets guns off the street and saves lives.