Written communication skills are one of the most assessed criteria in higher education contexts, especially in humanities disciplines, including teacher education. There is a need to research and develop an assessment grading tool (i.e. criteria sheet or rubric) that would assist students in pre-service teacher education programs to better understand and practice written communication and to assist markers when grading academic essays that include this criterion. When rubrics are used the criterion that covers the written communication skills part of the task is often too general to truly assist students to know what they must do in order to obtain the grade to which they aspire. Using substantive conversation in focus group discussions, we defined written communication and designed a criteria sheet using a model known as the Continua model of a Guide to Making Judgments (GTMJ). We found that this tool not only had the potential to help students to better understand key features of good written communication in an academic context, but also to assist assessors to focus on standards descriptors or 'threshold' qualities of written communication when grading students' academic essays.