Abstract
Writing tutors often have very little or no expertise in conventions of engineering writing. In this study, I examine the topics and politeness strategies of tutors' comments, investigating how non-expertise in engineering writing decreases the effectiveness of tutors' interactions with engineering students. I show how the three non-expert tutors gave inappropriate advice and often stated their advice with certainty. I also show how a tutor with expertise in engineering writing gave specific and useful guidance to her tutee and built rapport with him as well. I outline how writing tutors could be trained to help engineering students better.