The success of alternative assessments such as the Vermont Assessment Program (VAP) is heavily dependent on the involvement and commitment of teachers. This paper focuses on the implementation of the writing portfolio component of the VAP in the classrooms of four teachers who have different knowledge and beliefs about teaching and assessment. The historical context and basic structure of the writing portion of the VAP are described. Vermont schools, which are predominantly rural, have a long tradition of local governance, teacher autonomy, and inclusion of students with disabilities in the regular classroom. Four experienced fifth-grade teachers, first-time implementors of the VAP, were studied to determine the effects of this policy on teachers in different contexts. These four teachers represent four different belief cultures: curriculum-oriented, process-inquiry, polytheoretic, and minimalist. There were varying degrees and types of influences in these four classrooms as a result of their first year of participation in the portfolio system. The teachers began with different beliefs and practices, approached the VAP task differently, and finished with different degrees of involvement at the end of the year. The influence of the VAP in the classrooms ranged from none to changes in organizational procedures, to students writing more and producing more kinds of writing, and to students engaging in a new process of reflection and self-evaluation. Results suggest the need for long-range, flexible, and multidimensional approaches to professional development and the implementation of alternative assessment. An appendix provides an analytical writing assessment guide. (Contains 4 figures and 18 references.) (SLD)