A multicenter collaboration for data collection and statistical analysis may be necessary to establish and validate a classification system based on empirically derived scores for specific pathologic observations. The endometriosis pain instrument may be a tool for some of those variables with regard to pelvic pain. A similar strategy for uniform collection of data for analysis of important factors also is necessary for infertility. The challenge of creating a satisfactory classification of endometriosis remains. The ability of the current classification schemes to predict pregnancy outcome or aid in the management of pelvic pain is recognized to be inadequate. Further revisions of the current classification scheme are anticipated as the understanding of how endometriosis contributes to infertility and pelvic pain evolves. In any revision of the classification system, use of empirically derived weights and breakpoints to define disease stages based on outcome data in larger clinical trials should be attempted. It is also possible that additional factors, such as CA-125 level or lesion characteristics, may be shown to play an important role in prognosis. If so, these must be accounted for in the classification scheme. Careful and consistent use of the recommendations of the American Society for Reproductive Medicine classification of endometriosis subcommittee should allow for collection of data for use in further revisions. It is possible that a classification scheme that is designed to predict outcome with respect to pregnancy may be totally inadequate in assessing patients who have endometriosis and pelvic pain. Factors found to be important in the assessment of pelvic pain may be different from those involved with the pathophysiology of endometriosis and infertility. The AFS form suggested for use in the management of endometriosis in the presence of pelvic pain allows for recording of variables such as depth of invasion, histology, and documenting adjunct investigations and preoperative physical findings. Such prospective data collection and review in large centers may provide a large clinical base from which to derive empirical point scores and breakpoints in a classification scheme.