School librarians often see their collections and programs as vital elements of the reading program in schools. Certainly, school librarians know that library collections filled with rich and varied texts help create eager and adept readers. But what if collections were seen as a teaching resource for writing instruction? Often, today's writing instruction lingers over the complicated process of writing. Instead of rigid patterns and molds to fill, students learn to write in a variety of genres. When studying grammar, paragraphs and sentences from published works provide a context for how students can organize and compose their own pieces. This approach, using great examples or what are often called "mentor texts" as writing models, can be modified to virtually any aspect of writing. The work of great writers and illustrators is already there to "mentor" students into writing wonderful pieces in all kinds of genres. By finding and organizing mentor texts, school librarians become the writing teacher's ally in developing young authors. This article discusses how school library collections and programs can support writing instruction. The author presents an example of teaching leads using mentor texts and describes how to develop a collection of mentor texts.