The aim of the study was to determine the nature of the organizational stress being encountered by school teachers and the effect of stress on the performance of school teachers. The study was related to the secondary schools of both public and private sector in Punjab which comprises nine divisions. The study delimited to private and public secondary schools of Lahore division. The study adopted the descriptive survey design using a sample of 1000 teachers drawn from 100 secondary schools from both public and private sector in Lahore division. From each school 10 teachers were randomly selected. Two rating scales were developed to collect data for the study. The percentage, mean, standard deviation and t-test were applied as descriptive and inferential statistics were used to analyze the collected data. Based on the study, it may be recommended that unwanted sounds and noise may be minimized in the school environment, training be imparted to the staff, workload should be equally distributed and necessary facilities should be provided at the schools.