The DAPPLE project (Dispersion of Air Pollutants and their Penetration into the Local Environment, www.dapple.org.uk) is being undertaken by a consortium of six universities and involves a multidisciplinary approach to characterise and understand short range urban atmospheric dispersion. In this project, extensive wind tunnel work has been conducted to support the field and modelling work. There have been five main goals: 1) to help design the field tracer experiments; 2) to help understand the flow and dispersion processes involved; 3) to review the sensitivity of these processes to small changes in boundary conditions; 4) to provide comprehensive dispersion and flow data-sets for model evaluation purposes; 5) to simulate some of the field experiments that were carried out in central London over a number of years. Some key outcomes of these activities will be summarised, with most attention focused on the development of understanding and the link that has with model development. The generic value of the work will be emphasised and priorities for further wind tunnel studies discussed.