Assessment can be powerful when teachers are able to analyse, interpret and use information in ways that enhance their teaching and programmes, and students' learning. A qualitative approach was used to investigate how teachers of Years 4-8 students analyse, interpret and use information gained from administration of the Progressive Achievement Test: Mathematics (PAT: Mathematics) assessment tool. Six teachers from two schools in a rural district, south of Auckland, participated in the study. Teachers at one of the schools had access to the NZCER online marking and analysis service; teachers at the other school did not. Data were gathered through a series of semi-structured interviews and the collection of relevant documents. Both schools had a longstanding commitment to PAT: Mathematics. However, once teachers passed students' stanine scores to management they were free to further analyse and use the information, or not, as they saw fit. It was concluded that a systematic and planned approach to the analysis, interpretation, and use of data is needed if students, teachers, schools and other stakeholders are to get full value from the PAT: Mathematics tool.