Writing is a complex, recursive and difficult process that requires strategic decision-making across multiple domains (Graham, 2006; Pritchard & Honeycutt, 2006). Students are expected to use this process to communicate with a variety of audiences for a variety of purposes.  Modelling and providing effective instruction is critical, especially in elementary grades, when students begin to experience difficulties in learning to write and use writing to learn content across the curriculum. Professional development can foster teachers' writing proficiency and in turn improve students' writing achievements. This mixed methods study examined elementary teachers' attitudes towards writing, perceptions of themselves as writing teachers, their students' attitudes towards writing and the extent to which these attitudes and perceptions improved after ten weeks of research-based professional development. Pre- and post-workshop surveys were administered to teachers, classroom observations were conducted, and students' writing portfolios collected to examine the quality of writing over the course of one semester. Results indicate that a majority of participants had positive attitudes towards writing, felt competent teaching some domains of writing (for example, generating prompts), but not all (for example, revising and editing). Recommendations include more involvement of teachers in developing the content and design of PD workshops.