This chapter first provides an overview of the distribution of painful comorbidities among persons with orofacial pain, in particular TMD-related pain, for which considerably more literature is available than for other orofacial pain conditions. The relatively scarce literature on comorbidities in orofacial pain conditions such as atypical odontalgia and burning mouth syndrome (BMS) suggests that these conditions show substantial overlap and similarities with TMD-related pain, both in the presence of painful and nonpainful comorbidities (e.g., psychological factors) and in the diagnostic, treatment, and prognostic effects of these comorbid factors. Hence, the literature discussed below on TMD-related pain could be considered a proxy for the literature on other orofacial pain conditions. Second, this chapter reviews studies that have demonstrated the effect of painful comorbidities on the occurrence and persistence of orofacial pain. We describe the relationship between psychological comorbidities and orofacial pain, with special emphasis on consideration of comorbidities (1) during clinical examinations, (2) when making a diagnosis, and (3) when designing appropriate treatment programs to reduce pain and dysfunction before chronic pain develops. © 2014 IASP Press. All rights reserved.