The 2015 reauthorization of the Every Student Succeeds Act (ESSA) placed a state-level 1.0% threshold on student participation in the alternate assessment based on alternate academic achievement standard (AA-AAAS). ESSA also stipulated that state education agencies (SEAs) may not impose on any local educational agency (LEA) a cap on the percentage of students administered an alternate assessment. Nevertheless, LEAs are required to submit information to the SEA justifying the need to exceed 1.0% and SEAs must provide appropriate oversight of these districts. The National Center on Educational Outcomes (NCEO), at the request of states, initiated a 1% Cap Community of Practice (CoP) as a private forum for regular videoconferences. A password-protected website was established by NCEO so that the 1% CoP states could learn how other states were approaching implementation of the ESSA 1.0% requirements, including oversight of LEAs, and to share resources and information with and among states that would further the purpose of the ESSA legislation in this regard. The purpose of this report is to highlight the work of states in the 1% CoP that have successfully reduced their alternate assessment participation rates of students with the most significant cognitive disabilities. It identifies the strategies, challenges, resources, and plans for the future of five states that volunteered to share these with the CoP in an effort to provide a collective base of knowledge about "what works" to reduce alternate assessment participation and improve appropriate assessment participation decision making for students with the most significant cognitive disabilities. [This report was written with contributions from: Robin Stripling, Tabitha Riendeau, Dan Wiener, Deb Hand, John Jaquith, Marcia O'Brien, Antoinette Dorsett, Sharon Heater, and Iris Jacobson. It was prepared in collaboration with the National Center on Educational Outcomes's (NCEO's) 1.0% Community of Practice (CoP).]