Their main target of concern: front-running mayoral candidate Bill de Blasio, who has said he would charge rent to some charter school operators that now get free space in public school buildings.
"I'm a firm believer that we need to reward excellence, not punish it by having us pay rent for our schools," said Sulma Arzu-Brown, the mother of a fourth-grader at Girls Prep Bronx, an all-girls charter school.
About 70,000 of New York City's 1.1 million public school pupils currently attend charter schools, publicly funded schools that are independently run.
In addition to charging rent, De Blasio, a Democrat who is leading Republican Joe Lhota by 50 points in recent polls, favors a moratorium on forcing traditional public schools to share their buildings with charter schools.
The so-called co-locations of charter and traditional schools have often been contentious, with parents at the traditional schools complaining that the charter schools draw more than their share of resources.
De Blasio's spokesman said Tuesday that the candidate "will work with all our schools, but he believes that well-resourced charter networks should pay for the use of school space, as charter schools do across the country, and he'll put a moratorium on co-locations until we can better assess their impact."
Lhota, a strong charter school backer, said as he mingled with charter school parents outside City Hall, "We need more of them, we can't burden them with paying rent, we can't burden them with saying they can't locate or co-locate in a public school. We need to wrap our arms around the charter schools and really understand how important they are."
Marchers chanted "No rent!" as they marched from Brooklyn to City Hall. Organizers with Families for Excellent Schools said more than 10,000 people participated.
Charter schools have expanded greatly under Mayor Bloomberg over the last decade. There were 17 charter schools when Bloomberg took office and now there are 183.
Some information from The Associated Press