Since the 1980s, composition studies have considered the steps to be taken before assessment: designing the test essay question. While large-scale assessment has little control over writing variables (such as students' learning styles, their reading ability, and their interpretation of the topic), the content or the topic of the writing prompt and the procedures for writing can be manipulated, or at least acknowledged. In 1984, A. C. Purves and his colleagues classified 15 dimensions of the writing task that could be brought to bear on a writing prompt. This list provides a sense of the options available even though only a few can be dealt with on any one test. Ways to overcome the problem of choosing an appropriate topic include: select a topic of more or less equal familiarity to all students; generate a pool of topics of similar difficulty; supply the information for the topic; and allow students to write about whatever subjects they care about and/or believe they have the most knowledge of. A study comparing three topical structures in the writing prompt found that their utility depended upon purpose. In the interests of consistency, topics across an assessment and the accompanying instructions should share several of the characteristics that reduce the risk of interpretations too different from the intentions of the task. Four questions can guide broad decisions about writing assessment design and furnish test developers with the raw materials to create fair and meaningful writing prompts: (1) To what degree will the assessment be content specific? (2) What are the rhetorical demands of the task? (3) What topical structure and level of specification should be used? and (4) How should the prompt look on the page? (A table listing the dimensions of a writing assignment is included; 23 references are named.) (RS)