Aims: To evaluate whether a biobehavioral intervention would be more effective than a self-care intervention or no intervention in reducing psychosocial distress, reducing pain, and improving functioning in patients with an acute myofascial temporomandibular disorder (m-TMD). Methods: Participants (n = 435) were from community dental clinics in the Dallas-Fort Worth Metroplex who were seeking treatment for their acute TMD symptoms and were recruited between 2008 and 2013. The participants were diagnosed using the Research Diagnostic Criteria for TMD (RDC/TMD) and assigned to a biobehavioral intervention, self-care intervention, or no intervention. Three outcomes were assessed: psychosocial distress, pain, and functioning; and treatment effectiveness was assessed according to TMD diagnosis. Outcome evaluations were conducted immediately postintervention as well as at 1 and 2 years postintervention. Analyses were conducted using two-level hierarchical multilevel linear models (MLMs). Results: Contrary to expectations, patients did not respond differently to the intervention based on their TMD diagnosis. Acute m-TMD patients, especially those with other comorbid TMD diagnoses, reported the highest levels of pain and pain-related symptoms and disability. They also exhibited poorer jaw functioning, especially if they were at high risk for chronic TMD. Conclusion: This study indicates that acute m-TMD tends to result in more severe symptom presentations, particularly if diagnosed in combination with other TMD comorbidities. Additionally, patients do not appear to respond better to biobehavioral or self-care intervention on the basis of their TMD diagnosis. Schlagwörter: acute myogenous pain, high-risk, psychosocial distress, RDC/TMD, temporomandibular disorder