Writing is central to academic development, permeates content area coursework and serves as both a vehicle for and a display of learning. For English learners (ELs), writing poses challenges, and teachers need preparation in how to understand and respond to these. This study reports 5 teacher inquiry processes that preservice teachers in one teacher education program used to learn more about their ELs and their writing performances, strengths, learning, preferences, and needs. The inquiry processes provided opportunities to develop knowledge of content and students (Ball, Thames, & Phelps, 2008), a key subdomain of the knowledge base of effective teaching.