The 21st-century job description for school principals requires greater areas of leadership and accountability utilizing student data to improve instruction as mandated by state legislative reforms. The Principal's accountability is measured using the principal evaluation system. The general problem is that many principal evaluation systems are not consistent with design, performance standards, or the implementation process. The principal evaluation system not seen as the priority to foster effectiveness, resulting in ambiguity on accountability and leadership efforts. Further research is needed to explore bringing awareness to the principal about his or her effectiveness and utilize the realities as a learning process through the Texas Principal Evaluation Support System (T-PESS). The purpose of this case study was to investigate whether the principals in Northeastern Texas' perception of effectiveness aligns with the performance standards of the T-PESS, and give voice to the evaluated principals on the legitimacy of the principal evaluation system. The study participants comprised 22 principals with five or more years in a leadership role and 10 or more in the field of education. The qualitative data collected for the study consisted of a semi-structured, one-to-one interview protocol and the document analysis, voluntarily provided 2014-2015 and 2015-2016 Principal Evaluation Summative Reports/secondary data set. Interview sessions were audio recorded to ensure accuracy in transcription and coding. The results provided a contextual view of leadership practices and the use of the evaluation system to measure the principals' effectiveness on student achievement and teacher pedagogy. The results revealed five factors to take into account when using the principal evaluation system to measure principal effectiveness; principal's job too complex, inconsistencies in measurement, evaluator biases, campus diversity irrelevant, and a campus need-assessment more accurately identifies the principal's effect on student achievement. Further results indicate the T-PESS is more comprehensive in identifying the principal's effect on teacher pedagogy. The conclusions indicated effective principals do the job regardless of evaluation but utilize it for accountability. Further research must consider all school districts, states, and principal levels for further generalizations, update preparatory program standards, and ensure the growth and development of future principals to the profession. [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/en-US/products/dissertations/individuals.shtml.]