Much research into assessment has concentrated on its role in learning and educational practice, issues relating to objectivity and reliability in assessment, and the political and policy implications of assessment more generally. The means by which assessors arrive at their judgement has received comparatively little attention and remains obscure. There has been a focus on factors relating to the product rather than the subjectively experienced process of assessment. A greater understanding of the process is important for the validity of assessment and its wider consequences for students and others. The aim of this study was to examine how assessors conceptualise and carry out the assessment of discursive writing produced by students in a higher education context. Semi-structured interviews were conducted with experienced lecturers in health care subjects. The interviews and the data analysis were approached from within a hermeneutic phenomenological tradition, involving both description and interpretation. The participants' descriptions provided an analogue of what they thought they did cognitively as they assessed. These texts were then subjected to interpretation negotiated with participants to develop an understanding of the assessment process. There were two main findings relating to how participants carried out the process of assessment. Firstly, they made use of a framework of meanings that appeared in part to arise from the practice of evaluating in terms of grade-bands. These were viewed as having categorical identities with discontinuities between them, as opposed to representing ranges within a continuous scale. The data suggested that there were changes in the aspects of writing to which assessors paid attention (content versus argument/integration and components versus the whole), and the kinds of judgements they made (quantitative versus qualitative), at different points along the grade band scale. Secondly, the participants made use of six categories of processes during the course of performing an assessment. Some were objective and analytical while others were more subjective and integrative. They were not carried out sequentially, but appeared to be determined by the demands of the assessment task and to serve a function of simplification. The variety of processes within each category, their co-occurring usage and interdependence, and the selective use (or awareness) of processes by different assessors may help to explain some of the apparent complexity inherent in the assessment task, and the difficulty that experienced assessors demonstrate when trying to explain what it is they do and how they do it.