DescriptionCharlotte Wolff began working on the PhD project Transitions and Their Impact on Teacher Expertise Development in July 2011. Her PhD supervisor is Prof. dr. Els Boshuizen and Dr. Jan van Bruggen offers additional supervisory support. The research looks at expertise development in the teaching domain by considering the knowledge structures, cognitive processes, and transitions (professional and personal) which impact teachers’ professional development at various stages in their career. Charlotte briefly introduces her background, her current research, and her upcoming pilot study, Seeing what teachers see: Exploring the use of eye trackers in teacher expertise studies. The main goals of the qualitative study are to: 1) establish the suitability of the eye tracking methodology in the classroom teaching context; 2) determine how well different eye tracking systems (stationary or mobile) capture teachers' visual perception and attention; and 3) gauge the effectiveness of combining eye tracking data with other methods, such as think aloud and questionnaires, to reveal covert cognitive and perceptual processes of expert and novice teachers.