The authors investigated what and how instructional practices are related to students' motivation and performance in writing. The participants were 6 teacher interns and their (N = 209) secondary-school students in Hong Kong. In a 3-session instruction unit, the teacher interns taught their students how to write an expository essay. The students completed the essay and then a questionnaire to report their motivation in the task and their perception of the instruction. Results of structural equation modeling showed that students' motivation mediated the effects of instructional practices on writing performance. The authors found that when the teachers adopted more motivating teaching strategies, the students were more motivated. When the students were more motivated, they, in turn, had better performance in writing. (Contains 1 table and 1 figure.)