This qualitative case study investigated three first-year teachers at one high school during 1997-98, examining what factors contributed to their success or failure during their entry year and describing the process of teacher identity formation, what factors influenced the identity they created, and how they interpreted lessons learned. Data collection involved three formal, semistructured interviews; a stages of concern questionnaire; written or audiotaped journals; formal classroom observations; semistructured interviews with students of the teachers and their mentor teachers; document analysis of teachers' educational philosophies written as part of their undergraduate teacher education coursework; and informal observations of teachers outside the classroom. The beginning teachers felt a sense of strangeness as the school year began; they were continually surprised by things they were expected to know that they had not been told about. The mentoring program began too late to help during the initial weeks, when it was most needed, so the beginning teachers muddled through with help from colleagues. Five factors were important in their success or failure: communication, mentoring, classroom savvy, discipline, and expectations of various power blocks. The paper presents a Power/Discipline/Expectations model to detail how the factors interact and discusses lessons learned from each of the teachers' experiences. Implications and recommendations for school districts and preservice teacher education programs are provided. (Contains 74 references.) (SM)