The United States Environmental Protection Agencys (EPA) contracted with ENVIRON International Corporation to develop an analytical approach to determine how the Integrated Risk Information System (IRIS) is used by non EPA decision makers and IRIS customers in general. The approach developed and used by ENVIRON was to identify categories of IRIS customers and determine how representatives within the categories use IRIS. Information was collected in several ways, and the primary method consisted of interviews with representative customers from nine different user categories. The information collected during those nine interviews provides the bulk of the findings presented in this report. It is important to note that the data set collected for this report is limited. The focus of the analysis was to collect representative information across a broad spectrum of IRIS customers, not to conduct a comprehensive survey. Accordingly, this report can only present the views of a small minority of users. However, the customers interviewed characterized themselves as the most frequent users within their company, agency, academic program, trade association, or organization. Thus, this report presents the views of a small but highly significant sampling of IRIS customers. The nine formal interviews and supplemental discussions with other customers resulted in some very evident and easily discernable findings.