The overall aim for this study was to describe how portfolio assessment in writing was set up by an experienced teacher, how she and the students assessed the writing portfolios, and how the assessment was communicated to parents and caregivers. This study used a case study methodology based largely on observation. The focus of this study was a Year 5 teacher, her students, and their understanding of portfolio assessment in writing. After each day in the classroom fieldnotes were rewritten and interviews transcribed. After data summaries were made the data were analysed and categorised. Overall the data were analysed to show the students' understanding of portfolios, their motivation and self assessment in writing. Data were also analysed to show the role of the teacher in portfolio assessment and the amount of work involved in her portfolio assessment. Furthermore, the portfolios were analysed to see how they showed progress in writing and facilitated further learning. Finally, data were analysed to show how information from the portfolio assessment was communicated to parents and caregivers.