Teachers at the Philadelphia Archdiocese's 17 high schools have rejected a proposed one-year contract.
They say the wage increase offered wouldn't cover the rise in medical insurance premiums.
The Philadelphia Inquirer reports the teachers' current one-year contract expires Aug. 31. Both sides have been trying to reach an early settlement limited to the issues of salaries and benefits.
The entire contract can be opened up if no agreement is reached by June 1. The details of the proposed contract were not disclosed.
Rita Schwartz, president of Local 1776 of the Association of Catholic Teachers, says the proposed agreement "went down in flames" during the union's general membership meeting Wednesday night.
The archdiocese said it was disappointed with the vote.
The union's last strike was in 2011.
