The Joint Council Initiative in the UK was set up to encourage interdisciplinary research between cognitive science and human computer interaction. This evaluates the Initiative and the success of the collaboration across disciplines. A lack of clarity of objectives and definitions in programme design is a severe restriction on the ability to evaluate achievement. The solution in this case was threefold: to develop a personal perspective on interdisciplinarity; to examine the internal consistency of the definitions used; and to collect empirical information on a broad range of indicators, supplemented by case studies. Copyright , Beech Tree Publishing.