The purpose of this qualitative descriptive study was to explore how end-of-course general education teachers in public high schools (grades 9-12) described cognitive fatigue during the preparation and implementation of standardized testing practices in a Texas urban public school district. Prior to this study, it was not known how Texas public high school end-of-course general education teachers described cognitive fatigue during preparation and implementation of the state standardized testing practices used to prepare students to pass the STAAR tests in a Texas urban public school district. The motivational control theory of cognitive fatigue used to reveal the origin and functions of fatigue guided this study. The first research question asked teachers to describe cognitive fatigue during test preparations, and the second asked about cognitive fatigue during the implementation of the test practices. The sample was general education teachers in a public high school (grades 9-12) located in a Texas urban public school district that teaches courses that have standardized tests that students must pass to become eligible for high school graduation. This qualitative descriptive study relied on two data sources--semi-structured interviews and a questionnaire--analyzed using thematic analysis. Results reveal that cognitive fatigue during test preparation increases as the test date approaches. Moreover, cognitive fatigue is less pronounced during test implementation. Further, teachers experience increased emotions, stress, burnout, and anxiety during test preparation. [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.]