A multidisciplinary team assessed five patients who alleged chronic medically unexplained multiorgan system symptoms described by idiopathic environmental intolerance allegedly triggered by exposure to solvents used in membrane roofing repair work on an office building. The event precipitated an incident of mass psychogenic illness (MPI). Treating physicians diagnosed irritant-associated vocal cord dysfunction (IVCD) and reactive airways disease syndrome (RADS) resulting from exposure. The authors conducted medical, psychological, and industrial hygiene evaluations. Air monitoring data for total volatile organic compounds obtained during the 2-day exposure period, measurements of emissions during membrane roofing repair at a similar site, mathematical modeling of air contaminant concentrations, and injection of tracer gas into the incident building revealed exposure levels well below those doses anticipated to cause clinical symptoms. There was no objective medical evidence validating symptoms. Review of the medical records indicated that the video laryngoscopy data, pulmonary function tests, and medical examinations relied upon by the treating physicians were inconsistent with published criteria for IVCD and RADS. Psychological evaluation identified defensiveness and self-serving misrepresentations of exaggerated health concerns associated with somatization and malingering. Each case had personality traits associated with at least one personality disorder. Social histories identified premorbid life events and stressors associated with distress. This is the first study to assess psychological predisposition, social interaction among the plaintiffs, and iatrogenic reinforcement of beliefs by diagnoses of pseudo-disorders associated with patient misrepresentation of exaggerated health concerns in an incident of MPI.