A longitudinal study of psychological disturbance in the affected population in Sri Lanka after the cyclone disaster of 1978 was carried out. The post-cyclonic stress identified among the rural communities after their return to the same destroyed environment was studied. Symptoms tended to be early or delayed in appearance. The degree of unpreparedness is postulated as the causes of the former. Group cohesiveness and feelings of community tended to delay the manifestation of symptoms. Realization of losses, family needs, and continued habitation in damaged homes acted as reminders and reinforcers. Morbidity continued to affect over half the population one year later. Early intervention within community settings after such disasters is recommended.