Alignment between IS and the business has been broadly acknowledged as key to IS and business success. Considerable work has been done on modelling the process of alignment between IS and business strategies and structures. However, the way in which alignment changes over time as external circumstances change is not well understood. Given the rapidly changing environment in which many businesses operate, this is a key concern. This paper develops an internal response lag model as a means of investigating the dynamics of alignment from the perspective of IS and business managers. The model is illustrated using a broad based questionnaire and a series of interviews. Initial research outcomes are positive, and therefore a programme of further research in this area is proposed.