A framework is developed to evaluate expected search length, an important measure of an information storage and retrieval system's performance, as a function of the size of the information file and its organization in terms of indexing search structure. Previous research pertaining to search length by W.S. Cooper and others is surveyed and extended. A conceptualization recognizing a dichotomy of retrieval activities--intellectual access versus physical access--is presented. Three cases are analyzed to demonstrate the benefits of indexing and organizing an information file. The applicability of such a model to library systems is demonstrated and potential areas for future research are identified. (Author/KP)