The existing clinical measures of disease activity for inflammatory bowel disease are insufficient to explain a patient's illness experience or health outcomes. Although many disease activity measures have been devised, they are not widely accepted by clinicians because existing ones are no better than a carefully obtained clinical assessment. Furthermore, health status is determined not only by disease activity, but also by the psychological state, cultural influences, degree of social support, and effects of complications, previous surgery, and medication. To develop more accurate appraisals of the impact and severity of IBD, we must prospectively evaluate the biological and psychosocial measures that predict clinically relevant outcomes. We should then be able to develop statistically weighted scales related to specific outcome variables. Such knowledge will help us to develop more sensitive measures of illness, particularly in patients with mild disease for whom present indices are insensitive. This type of assessment should also aid in the understanding of health care utilization, medical vs. surgical options, resource allocation, and the efficacy of therapeutic trials.