The protesters are angry the county is considering using two youth probation camps, Afflerbaugh and Paige, as newly designated secure youth treatment facilities.
The probation oversight commission says the permanent site it chooses will undergo significant security upgrades.
But concerned residents say there are much better locations than the middle of a neighborhood.
"The county's trying to put this in under the radar but everybody found out about it," said Judy Turnquist of San Dimas. "We don't want it here. It's fine that it's a place for youth that are having problems, but not murderers and rapists and kidnappers."
The commission plans to hold a virtual town hall on the issue Tuesday.
The city council of La Verne has gone on record to oppose the location of the camps.