This study emerges from the claim that identification of patient subgroups will advance our understanding of IBS and ultimately help develop treatment approaches. Most studies have lumped together patients with IBS into 2 groups (constipation-, diarrhea-predominant) and tested whether they differ from healthy controls. We propose that a paradigm shift is in order. We should recognize that IBS likely has multiple causes and therefore, multiple expressions. We speculate that by understanding better defined patient subgroups and linking them to newer biomarkers or tests, ultimately will further the understanding of the origins and create effective treatments.