Classroom assessment of writing is considered from an anthropological perspective as practitioners' tool use. Pan Canadian data from a 2002 English teacher questionnaire (N = 4070) about self-reported assessment practices were analyzed in terms of tool choice and use by secondary teachers of different experience and qualification levels. Four underlying variables were identified in their choice of assessment tools: whether affective traits such as attendance, effort, motivation or participation were factors; whether self-assessment and peer evaluation were considered; whether portfolios or examples of student work were variables in grading practices; and whether multiple choice or short response tasks were chosen. In terms of tool use, the three salient variables were: the nature of the feedback cycle with students; whether homework contributed to grades; and whether homework served in large group instruction. A number of significant differences by career stage and credential level were revealed in assessment instrument choice and use. Implications for teacher pre-service and in-service professional development are outlined. (Contains 10 tables.)