The purpose of this study is to clarify the role of internal and external factors in elementary and secondary school principals' perceptions of on-the-job stress. Variables include school location, school type, the principal's gender, and the principal's work experience. Of 300 questionnaires mailed out to New York State school principals, 235 were returned, including 72 urban, 85 suburban, and 78 rural school principals from 114 elementary and 121 secondary schools. According to the modified Administrative Stress Index used for the study, principals generally perceived a greater amount of job stress from interactions with external groups, such as parents and union representatives, than from interactions with superordinate internal groups, such as school board members and superintendents. Results confirm the findings of previous studies, however, indicating that interactions with subordinate internal groups, especially teachers, generate the greatest amount of stress. School location, school type, the principal's gender, and the principal's work experience were not found to be significant variables. The study also confirms previous findings that the majority of principals do not consider their jobs highly stressful. Findings are summarized in 13 tables and charts. (JBM)