In early May 1966 several secondary schools in the Dar es Salaam region of Tanganyika reported sudden episodes among groups of girls: fainting, dizziness, hyperventilation, nausea and weakness. The events occurred over days and spread between classrooms and schools. Local authorities temporarily closed some schools and summoned medical teams to examine affected pupils. Newspaper coverage at the time emphasized the alarming appearance of the episodes; official investigations were carried out to determine whether a physical agent—such as infection, food poisoning or environmental toxin—was responsible. Clinical assessments by physicians, combined with epidemiological observations, produced key features that guided subsequent interpretation. Symptoms were transient, primarily functional rather than consistent with a single organic pathology, and were disproportionately concentrated among adolescent girls. Although dramatic in presentation, objective clinical signs were generally absent or inconsistent with a specific physiological cause. No reproducible laboratory or environmental evidence emerged to implicate a pathogen or toxin. Cases often began after an initial index episode and then spread by visual and social contact, consistent with contagion of symptoms rather than contagion of disease. Scholars later classified the outbreak as mass psychogenic illness (MPI), sometimes called mass sociogenic illness—an occurrence in which groups of people develop similar physical symptoms with no identifiable organic basis, often in contexts of stress, anxiety or social suggestion. MPI has been documented in schools and work settings worldwide, particularly among adolescents and young adults. The 1966 Tanganyika episodes are cited in public-health literature as an early, well-documented example from Africa and as illustrative of the sociocultural dynamics that can shape symptom onset and transmission. Contemporary observers noted several contextual factors that may have contributed: rapid social change following independence (Tanganyika gained sovereignty in 1961), tensions around schooling and gender roles, crowded classrooms, and heightened public anxiety amplified by media reports. Researchers caution that labeling an event as psychogenic does not imply that symptoms were feigned or unimportant; affected individuals experienced real distress and required clinical care, reassurance and social support. Public-health responses that incorporated clear communication, calm clinical evaluation, and temporary adjustments to school routines were effective in helping reduce symptom spread in many comparable events. Limitations and uncertainties remain in retrospective accounts. Detailed clinical records, systematic environmental testing, and comprehensive sociological data from 1966 are limited, and some contemporaneous reports may reflect incomplete investigation. Nonetheless, the balance of clinical, epidemiological and sociological evidence in published reviews supports an interpretation of the Tanganyika episodes as mass psychogenic illness rather than an outbreak caused by a pathogen or toxin. The 1966 episode has continued relevance: it highlights how social context, stress and observation can produce clusters of physical symptoms, and why rapid, compassionate public-health responses that avoid sensationalism are important. Modern clinicians and public-health officials still draw on historical cases like Tanganyika 1966 when designing interventions to manage and communicate about unexplained symptom clusters in schools and communities.