The network operates a middle school and three high school son Chicago's northwest side. They serve roughly 1,800 mostly-Latino students.
Teachers said they've been negotiation a new contract for nearly 10 months, and say they will strike if talks remain at an impasse.
"Our teachers and educational staff are the backbone of Chicago's charter schools, and ASPIRA educators have taken this serious step today because they feel they must to protect their classrooms," said ChiACTS Local 4343 president Chris Baehrend.