This workshop introduces a framework for diagnosing foreign language reading skills (Alderson et al., 2015). The session will cover the foregrounding principles and stages in diagnostic testing: observation, initial assessment, hypothesis testing, decision making and feedback. By looking at individual student differences and bottom-up reading processes, teachers can identify learner strengths and weaknesses to support them in reading challenges and development opportunities. Tasks from various diagnostic tools will be trialed through experiential learning activities.