Although the integrated library system (ILS) increasingly dominates the information activities of library staff and users, there are very few objective measures available by which to evaluate its medium to long-term impact. This article moves towards the production of a simple, numerical index of ILS evaluation. It applies a variety of context-dependent evaluation methods to the different phases of the ILS lifecycle culminating in a 'draft' index of evaluation. Although this methodology and index should not be regarded as a finished product, it should act as a useful starting point for further, comparative studies, particularly those that seek simple ways to incorporate relevant, non-subjective criteria into the ILS evaluation process.