Although audience plays an important role in all models of writing, there has been little research on how second language (L2) writers conceptualize and address their audience during the writing process. This study starts to address this research gap by examining when and how L2 learners consider their audience while writing in L2, as well as the effects of writing audience on their writing processes and texts. Each of 16 L2 learners at two levels of English language proficiency (low and high) responded to four writing tasks that involved writing emails to audiences that differ in terms of their familiarity and status relative to the writer. Each participant then watched a video recording of their writing session immediately after completing each email and provided stimulated recalls about what they were thinking while writing the email. The emails were analyzed using a multidimensional analysis approach, while the stimulated recalls were coded in terms of various writing processes (e.g., task conceptualization, considering audience, revising). Findings indicated that when writing to unfamiliar readers, the participants tended to plan, monitor, and revise their texts differently than when writing to familiar audiences. The linguistic characteristics of the emails the participants wrote also varied across audiences and groups. The findings and their implications for L2 writing instruction, assessment, and research are discussed.