The purpose of this study was to determine what leadership responsibilities principals of successful middle level schools in Texas perceived as most essential to student achievement. The study was also intended to reveal how closely these principals? leadership responsibilities align with the literature. The Texas Academic Excellence Indicator System (AEIS) data were analyzed from 2005 to 2008. From this data, middle school campuses with 500 or more students, a free and reduced lunch rate greater than 50%, and AEIS ratings of ?exemplary? three of four years were identified. Thirty-nine campuses met the criteria and 15 of the principals agreed to serve as the expert panel. Using a modified Delphi technique, panelists completed a 26-item questionnaire and an open-ended comments section. This comprised Round One of the study. Data were analyzed for mean, median, standard deviation, and inter-quartile range (IQR). Unique questionnaires were developed based on panelist responses from Round One. Panelists were to review their responses to questions falling outside of the IQR and were able to change or maintain their responses after reviewing the data. Panelists repeated this procedure reviewing all questions with responses outside the IQR for Round Three. The major findings of this study revealed many of the critical leadership responsibilities are supervisory and not instructional. The five leadership responsibilities (ties are denoted) perceived by panelists as most critical to student achievement were: (1) ethical behavior, (t2) collaborative processes, (t2) visibility, (t3) collective vision, (t3) high expectations, (t3) instructional supervision, (4) professional development, and (5) intellectual stimulation. Through all three rounds, ethical behavior was identified as the most critical leadership responsibility. The findings of this study may potentially impact hiring practices of middle level campus leaders as well as their certification programs and professional learning opportunities. It is recommended principal preparation programs require an ethics course, and school districts provide annual ethics training for leadership teams. Additional professional learning should include team and collaboration building. Finally, based on the literature, it was recommended a principal certification specifically for middle level leaders be offered and/or middle level course work be included in the principal certification program.