Irritability is a transdiagnostic phenomenon that, despite its ubiquity and significant impact, is poorly conceptualised, defined and measured. As it lacks specificity, efforts to examine irritability in adults by using a diagnostic category perspective have been hamstrung. Therefore, using a Research Domain Criteria (RDoC) approach to examine irritability in adults, which spans many constructs and domains, may have a better chance of yielding underlying mechanisms that can then be mapped onto various diagnostic categories. Recently, a model has been proposed for irritability in children and adolescents that uses the RDoC framework; however, this model, which accounts for chronic, persistent irritability, may not necessarily transpose to adults. Therefore, use of the RDoC framework to examine irritability in adults is urgently needed, as it may shed light on this currently amorphous phenomenon and the many disorders within which it operates.