While the last decade has witnessed a growing body of research on student motivation in second language acquisition, research about the impact of writing instructors' motivational strategies on student motivation has remained underexplored. In order to fill this important gap, this study, guided by motivational strategy framework, investigates the effect of writing instructors' motivational strategies on student motivation. Participants were 344 first-year undergraduate students taking a writing course at a university in Singapore. Classroom observation schemes, student surveys, and surveys with writing instructors were collected. Findings show that the more the writing instructors reported using strategies in generating students' initial motivation in the classroom, the more the students reported having positive attitude and improved self-confidence in the writing course. This study contributes new knowledge to the field by relating writing instructors' motivational strategies to students' positive attitude in learning, the feeling of success in written assignments, and their self-confidence.