This chapter provides a teacher-friendly snapshot of how Complexity, Accuracy and Fluency (CAF henceforth) have become key dimensions of writing proficiency or writing quality over several decades of second language research. We frame this snapshot around a common framework, that of the Common European Framework of Reference (CEFR). The chapter draws on widely accepted definitions of CAF dimensions and highlights how they present themselves in CEFR rubrics. The chapter then builds on this by describing and critiquing how CAF has often been measured in research studies. We offer several practical suggestions on how early-career teachers can advise their learners on CAF dimensions and how teachers can implement CAF into the tasks they design. We conclude our chapter by posing several questions that promote ideas for CAF action research which teachers could carry out in their own unique contexts.