Central American women and children fleeing violence in their homelands seek asylum in America, the advocates said, but are treated like criminals.
The bishops recommended replacing the practice with alternative detention programs that would give back immigrants their dignity and due process.
The Obama administration's policy of detaining immigrant women and children seeking asylum in the U.S. could soon end.
"Children, many of whom are babies and toddlers, do not belong in jails, nor do their mothers, who've acted only to protect and save the lives of their children."
The traditional Lenten practice of fasting is being paired with the latest round of Fast for Families, intended to bring attention to the campaign for immigration reform.