The effect of the leadership style of the secondary school principal on student achievement in select public schools in Louisiana was examined in this study. The null hypothesis was that there was no statistically significant difference between principal leadership style and student academic achievement. The researcher submitted the LEAD-Self online survey to thirty-three principals in thirty-four public school districts in Louisiana. Fourteen of the thirty-three principals responded for a response rate of 42%. The leadership style of secondary-level school principals was self-assessed using the LEAD-Self (Leadership Effectiveness and Adaptability Descriptive) online survey. The LEAD-Self contained twelve scenarios. Principals were asked to respond to each scenario by selecting one of the four responses. The LEAD-Self measured leadership range and ability to adapt leadership behavior to varied situations. Data provided adaptability rates corresponding to democratic, autocratic, and laissez-faire styles of leadership. Based on responses, eight principals were classified as democratic. Four principals were classified as autocratic, and two as laissez-faire in their approach to leadership. The classifications were based on the frequency of responses in the telling, delegating, selling, and participating quadrants in the LEAD-Self profile report. Descriptive and inferential statistics were derived from the Mann Whitney U and Kruskal-Wallis One Way ANOVA. Based on the statistical calculations, there was not a statistically significant relationship between principal leadership style and student achievement at the 0.05 level of significance. The null hypothesis was that there was no statistical significance between student achievement and secondary-level principal leadership style. The null hypothesis was accepted. However, a strong relationship did emerge between Adaptability Rate and Leadership Style suggesting that leadership style and adaptability were favorably related. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]