Shortages of qualified principal candidates and retention of motivated principals, combined with the evidence that the principal is a vital part of effective school improvement, has ominous implications for the future quality of education. A body of research exists describing school administrators' stress over the last 25 years; yet, limited research reflects the impact the changing role of the principal in the accountability era of "No Child Left Behind" has had on principal stress and the possible connections to the shifting paradigms in organizational leadership. If principals perceive themselves to be overstressed and unprepared to meet the current expectations and challenges of the position, then it becomes more difficult to find people desiring to lead our schools, to keep us competitive in our global community, and to prepare our students for the future. This study utilized two conceptual lenses to address school principals' stress, new science organizational theories of chaos and complexity and transactional stress theory. Transactional stress theory helped to describe the relationship between principals and their perceived environmental stressors. New science theories provided a basis to view principal stress from an organizational leadership perspective. The following research questions guided the study: (1) "What are the perceived stressors of principals in Nevada"? (2) "What are the perceived differences in the intensity and types of principal stressors identified prior to and following the implementation of No Child Left Behind"? (3) "What differences in perceived principal stressors are related to school and principal demographics"? (4) "Which perceived stressors may reflect conflicting paradigms between the current construct of our educational system and the expectations of leading school improvement in the globally interconnected and dynamic environment in which we live"? Descriptive survey methodology was used for this study. Active public school principals in the state of Nevada were included in the sample. The 35 item Likert scale Administrative Stress Index developed by Gmelch and Swent (1984) was utilized to collect data, along with additional Likert items and open-ended and demographic questions designed by the researcher. Descriptive and inferential statistics were used to analyze and report findings from the demographic and Likert scale questions and qualitative coding methodology was used to analyze open-ended questions. A total of 256 surveys were completed for a 45% return rate. Study findings revealed the participants' highest reported stressors were related to the "No Child Left Behind" accountability reforms. Connections between principals' perceived stress and conflicting organizational paradigms are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]