The increasing reliance of organizations on information technology, which prompts everyone to expect faster responses to information needs, is propelling end users to satisfy many information requests they receive by querying databases themselves. This paper develops and tests a model for the effects of information request ambiguity on end-user query performance where performance is measured by the number of errors in user- developed queries, the time taken to complete queries, and end usersí confidence in the correctness of their queries. Based on preliminary analysis of participantsí performance, end-user query performance was significantly degraded by the presence of ambiguity in information requests. The model identifies seven ambiguities: lexical, syntactical, inflective, pragmatic, extraneous, emphatic, and suggestive. Organizations whose participants rely on e-mail to communicate information requests or whose work teams experience rapid personnel turnover may be especially vulnerable to the debilitating effects of ambiguities on information requests.