A common theme has been consistently woven through the literature on teacher professional development: that practice-based designs and collaboration are two components of effective teacher learning models. In addition to collaboration and practice-based designs, inquiry cycles have been long recognized as catalysts for teacher professional development. This article describes a practice-based and collaborative inquiry professional development model that is an adapted form of lesson study. A typical lesson study involves teachers in cycles of collaborative inquiry though topic selection, lesson design, observations of lessons, analysis of data from observed lessons, and application of new knowledge to inform the next cycle. This study sought to contribute to the literature by following five middle school English language arts teachers through three years and nine lesson study cycles focused on teaching and learning writing. The following research questions were addressed: (1) How, if at all, does a practice-based learning model afford opportunities for pedagogical reasoning and action?; and (2) What, if any, pedagogical shifts did teachers make and sustain beyond the lesson study? This study involved three years and nine cycles of lesson study. Each collaborative cycle included topic selection, lesson design, lesson observation, observation debrief, and the analysis of student learning from the lesson. Data for this study were drawn from a three-year lesson study project that spanned from 2008 to 2011. Follow-up interviews in spring 2013, two years after the lesson study project ended, revealed that all five participating teachers maintained and/or expanded what they learned in the lesson study. Additionally, during the two-year period after the lesson study, each participant presented ideas generated by the lesson study to outside audiences. Findings from this present study suggest that practice-based teacher professional development models hold great promise for making lasting pedagogical shifts and for incorporating pedagogical reasoning and action into the daily practices of teachers.