Since 2001, U.S. states have mandated that principals in unsuccessful schools author a school improvement plan (SIP) using the rational model of planning. Research on their efficacy is sparse and evidence suggests that principals satisfice on these SIPs, producing work that is "good enough" to meet concerns for external legitimacy over prioritizing internal needs. Because the sensemaking that is triggered in principals by mandated amelioration efforts occurs in the context of their local environment, both sensemaking and institutional theory offer a lens to study the problem of principal satisficing. By adapting Maxwell Yurkofsky's responses to a continuous improvement process and Mia Raynard's complexity configurations, this study examined the lived experience of ten principals leading Pennsylvania public high schools identified as Additional Targeted Support and Intervention (A-TSI) schools. Principals who described their environments as less complex responded to the written SIP in ways that only prioritized internal needs. Principals who described their environments as more complex responded to the written SIP in ways that prioritized both. When principals perceived that the global COVID-19 pandemic increased the complexity of their institution, they responded in ways that only prioritized concerns for external legitimacy. This study contributes evidence to the field that the rational model of planning may be insufficiently effective as an improvement tool in schools with high institutional complexity. [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.]