Objective: Outbreak investigations are challenging in a cross-cultural context, and outbreaks of psychiatric disease are rare in any community. We investigated a cluster of unexplained debilitating illness among Amish girls. Method: We reviewed the medical records of cases, consulted with health care providers, performed active case finding, administered open-ended and structured interviews, and met with Amish community members. A case-patient was defined as a resident of the county who was bedridden for more than 3 weeks with otherwise unexplained systemic weakness and anorexia from January 2000 to February 2002. Results: Five case-patients were identified. All were Amish girls aged 9 to 13 years. All five had debilitating voluntary motor deficits, anorexia, and weight loss. Four experienced neck weakness with inability to hold up their heads. Thorough medical evaluations failed to identify an organic etiology. All five patients met the diagnostic criteria for conversion disorder. Substantial social conflict within the Amish community preceded illness onset. Family behavioral interventions were recommended. Three months after the investigation, four of five patients demonstrated some improvement. Conclusions: Clinicians should be aware of the potential for outbreaks of psychogenic illness and work to address the challenges of developing effective intervention strategies, particularly in the cross-cultural context. J. Am. Acad. Child Adolesc. Psychiatry, 2005;44(3):291-297. Key Words: outbreak, conversion disorder, Amish, cross-cultural.