Generalizing has been identified as a central practice in mathematical reasoning; however, research has highlighted the challenges that students encounter when engaging in this practice. In this presentation, I share findings from my doctoral research study that explores teacher learning about selecting tasks that foster generalization in a professional development (PD) workshop. The workshop was designed using a novel instructional model in which teachers learn about tasks that foster generalization by developing knowledge of generalizing as a mathematical practice. I describe the learning of one in-service secondary mathematics teacher who participated in the PD. Initial analysis found that the participant generalized in increasingly sophisticated ways as the workshop progressed and revised tasks in ways that would engage her students in similar generalizing activity. These findings contribute to the field’s understanding of how to design professional development that supports secondary mathematics teachers in engaging students in productive generalizing activity.