The use of contract teachers is pervasive in Korean schools, especially inprivate schools. While contract teachers are temporary teachers, both in publicand private schools, private school teachers have incentives to work harder toget a permanent job offer. This implies that public school contract teachersmay have negative effects on students’ academic achievement, but privateschool contract teachers may have either positive or negative effects. Thispaper estimates the effects of contract teachers on students’ academicachievement and school satisfaction. The findings indicate that public schoolcontract teachers have negative effects on Korean and English test scores,while private school contract teachers have positive effects on the test scoresof the two subjects. No effects were found on math test score. In addition,contract teachers had positive effects on school satisfaction in private schools,but had no effects in public schools.