Research into extensive reading (ER) has provided evidence of gains in fluency, vocabulary development, and improved motivation. However, since reading literacy is such a complex phenomenon, what about the performance gaps for our learners that go unaddressed with basic ER principles? This presentation briefly covers a four-stage framework for diagnosing foreign language reading skills (Alderson et al., 2015) — observation, initial assessment, hypothesis testing, decision making and feedback. The session then highlights three fundamental underpinnings—the science of how we read, individual differences, and bottom-up reading processes. With a greater understanding of these three, teachers can identify learner strengths and weaknesses to better support them in their reading challenges and development. Online links and various diagnostic tools will be shared and trialed for practical, ‘learning by doing’ in experiential learning. Participants should take away a broader sense of issues their learners may face with reading and resources to implement following diagnoses.