A sense of audience is important in the development of student writing (Many & Henderson, 2005). Research shows students need to consider an audience's attitudes, beliefs, and expectations to be effective writers (Midgette, Haria, & MacArthur, 2007). Therefore, students need learning opportunities in L2 classrooms to develop this ability. Yet, the incorporation of audience in L2 textbook writing activities has not been sufficiently addressed. This study examined textbook activities to whom students write based on parameters of audience influence proposed by Grabe and Kaplan (1996, 2014). Writing prompts from six high school textbooks in Saudi Arabia were analyzed. The results indicate prompts instruct students to write to a single reader, known/unknown readers, as well as write about general topics. However, prompts do not provide information for students about three parameters (age, gender, and social status) which are necessary ingredients in developing a writer's sense of audience and play a significant role on textual variations. This study also modified a model of audience that can be used for textbook evaluation. The findings benefit textbook developers and teachers by motivating them to consider parameters of audience influence when they design lessons and materials for L2 writing classrooms.