Two studies were designed to investigate the age at which students adapt expository writing to meet the needs of different audiences. In the first study, students in grades four, eight, twelve, and at university level wrote descriptions of geometric figures that would enable someone unfamiliar with a figure to draw it. For all grades, realistic communications (including feedback drawings made from descriptions) contained more audience-oriented statements than "classroom exercise" descriptions which were less realistic. When the age of the intended audience was given, descriptions from students of grades 12 and higher contained audience-related statements, but those statements were not strongly related to the quality of information in the description. In the second study, which consisted of student revisions of their own compositions, fourth graders made no significant changes, while eighth graders made changes that reduced the quality of the descriptions. Only twelfth graders made changes that increased the quality of the revisions. Results from both studies suggest that not until grade 12 do students apply information of a general nature to effectively modify their writing. (Author/RL)