Background or Context: Amid a backdrop of increasing deprofessionalization of teaching and teacher education, education researchers and reformers continue to highlight the complexity and expertise of these professions. Expertise-as-process (Bereiter & Scardamalia, 1993) is a conception of expertise that eschews the traditional focus on accumulated knowledge, emphasizing instead expertise as a process of identifying new challenges and using challenges to continue learning. Although this conception has been used to inform thinking regarding expertise more broadly, it has rarely been applied in empirical studies of teaching and teacher education. Purpose, Objective, Research Question, or Focus of Study: Using expertise-as-process as a framework for analysis, this instrumental case study focuses on one expert literacy teacher/teacher educator who enacted expertise as a continual learning process. Research Design: The case study draws from 18 months of data collection to examine the lived enactment of expertise-as-process through praxis. The study focuses on the focal participant’s planning, teaching, professional learning, collaborative discussions, and recollections of her 20+-year career as a high school English teacher and teacher educator. Conclusions or Recommendations: The focal participant enacted progressive problem-solving by engaging in complex thinking about teaching and students, actively seeking opportunities to improve her teaching, and involving collaborators in these pursuits. This approach to teaching was accompanied by diverse emotions: passion, care, anxiety, and dissatisfaction. This case study provides a detailed picture of an expert teacher’s practice across domains through a theoretical lens rarely used to understand expertise in the teaching profession, and adds a needed emotional dimension to the research on teacher expertise and on expertise more broadly.