Work in progress is reported for a research project aiming to improve multiprofessional teamworking in operating theatres through iterative educational intervention. Experimental design is combined with collaborative inquiry. The hypothesis is: will planned, complex educational intervention focused upon improving communication in teamwork lead to better patient safety? The project is embedded in a wider educational agenda promoting democratic working practices, and this is reflected in the participative inquiry aspect of the research where operating theatre staff take ownership of the project through establishing common meanings for "good practice". The cohort involves 300 personnel (surgeons, anaesthetists, nurses and support staff) spread across two theatre complexes (11 theatres in total) in a large UK hospital. The focus of this paper is necessarily upon design and methodology, as the first data set is being gathered and analysed at the time of writing. Future papers will focus upon results and offer conclusions and recommendations.