In this research, we examine strategies school principals have used to assist struggling teachers. In an open-ended questionnaire designed for this study, we asked 219 school principals to describe a successful intervention they held. The results show that principals prefer supportive assistance to organizational changes (such as moving the teacher to another class). They rarely used confrontational approaches. A content analysis of the strategies that enabled successful intervention identified four conditions: (a) principals' willingness to intervene; (b) intensive use of measures and resources; (c) the teacher's willingness to make changes; and (d) the need for flexibility in managing the intervention. The findings indicate the need to train principals to assist struggling teachers more effectively and to encourage them to become more assertive. This requires a professional development program for teachers and principals, guidance in classroom management, as well as organizational, financial, and human support.