This study explored the practice of "teacher-volunteerism" in Ontario, Canada. A teacher-volunteer refers to those teachers who are fully certified to be employed as teachers in Ontario and who remain active in the teaching labour market. Teachers in Ontario, facing a competitive labour market, have increasingly volunteered inside of schools. Drawing on qualitative interviews with unemployed and underemployed teachers in Ontario, the paper examines and discusses experiences concerning volunteerism within this context. Findings revealed that teacher-volunteerism is largely motivated by employment-related concerns, with volunteers engaging in various teaching-related practices inside of schools. Teacher-volunteerism is understood as a new expectation faced by un(der)employed teachers as they seek paid employment. The exploration of teacher-volunteerism leads to further interrogation surrounding the intersections of teachers' work and labour in the field of education.