The strike began on October 17, 2019, when both unions failed to reach a contract agreement with Chicago Public Schools over compensation, benefits, staffing, wrap-around services such as counselors, nurses, and librarians, and caps on class sizes.

[2][3] On October 31, the strike officially ended when the mayor and the Chicago Teachers Union reached a tentative agreement allowing students to go back to class on November 1, 2019.

[4] The agreement included millions of dollars dedicated to reducing class sizes, hundreds more social workers, nurses and librarians, and a 16 percent salary increase over the coming five years, but did not achieve all the main goals of the unions.

[6] On September 24, 2019, CTU hosted a rally alongside SEIU Local 73 representing school support staff and Chicago Park District workers featuring Vermont senator and presidential candidate Bernie Sanders.

[10] The union's top priorities in contract negotiations are reducing classroom size and increasing the number of support staff such as nurses, librarians and social worker.

[13][14] On October 14, 2019, the CTU and SEIU Local 73 held a rally for a fair contract in downtown Chicago 3 days before the strike.

The union delegates voted to reject the district's latest contract proposal leading to the beginning of a joint strike with SEIU Local 73 at 12:01 am on October 17[2] leaving roughly over 300,000 students out of school.

Massachusetts senator and 2020 presidential candidate Elizabeth Warren joined teachers on the picket line outside Oscar DePriest Elementary School in the South Austin neighborhood.

[23] On October 29, The CTU and SEIU marched to the Sterling Bay headquarters to demand that the development return TIF funds given to the company that should have gone to schools.

Chicago police said they were called just before 2 p.m. to a building in the 1300 block of West Fulton "where numerous individuals were inside and refusing to leave."