Very few studies have so far tried to estimate teacher value added in England, mainly because there is no systematic collection of student attainment data, other than for statutory assessments in Years (grades) 6 and 11. The Teaching Improvement through Data and Evaluation (TIDE https://niot.org.uk/research-projects/teacher_improvement_through_data_evaluation_tide) project hopes to break that impasse using results from common assessments, taken up to three times a year in a wide range of subjects. These are internal assessments, used by the schools to monitor student progress, so we have had to address challenges of data access and assessment quality. Matching attainment data with school timetable and HR data, along with workforce surveys, allows us to address a range of questions not previously tackled in England, and some that have not been addressed anywhere. The webinar will outline the project aims and methods, and present some preliminary results of our analyses.