The Every Student Succeeds Act (ESSA) of 2015 (Public Law 114-95) requires each state to create a plan for its statewide accountability system. In particular, ESSA calls for state plans that include strategies for reporting education outcomes by grade for all students and for economically disadvantaged students, students from major racial and ethnic groups, students with disabilities, and English learners. In their plans, states must specify a single value for the minimum number of students needed to provide statistically sound data for all students and for each subgroup, while protecting personally identifiable information (PII) of individual students. This value is often referred to as the "minimum n-size." Choosing a minimum n-size is complex and involves important and difficult trade-offs. For example, the selection of smaller minimum n-sizes will ensure that more students' outcomes are included in a state's accountability system, but smaller n-sizes can also increase the likelihood of the inadvertent disclosure of PII. Similarly, smaller minimum n-sizes enable more complete data to be reported, but they may also affect the reliability and statistical validity of the data. To inform this complex decision, Congress required the Institute of Education Sciences (IES) of the U.S. Department of Education to produce and widely disseminate a report on "best practices for determining valid, reliable, and statistically significant minimum numbers of students for each of the subgroups of students" [Every Student Succeeds Act of 2015 (ESSA 2015), Public Law 114-95]. Congress also directed that the report describe how such a minimum number "will not reveal personally identifiable information about students." ESSA prohibits IES from recommending any specific minimum number of students in a subgroup (Section 9209). IES produced this report to assist states as they develop accountability systems that (1) comply with ESSA; (2) incorporate sound statistical practices and protections; and (3) meet the information needs of state accountability reporting, while still protecting the privacy of individual students. As presented in this report, the minimum n-size refers to the lowest statistically defensible subgroup size that can be reported in a state accountability system. Before getting started, it is important to understand that the minimum n-size a state establishes and the privacy protections it implements will directly determine how much data will be publicly reported in the system. Appended are: (1) Sampling; and (2) ED DRB Data Protection Schema.