These are the appendixes for the report "Children's Knowledge and Skills at Kindergarten Entry in Illinois: Results from the First Statewide Administration of the Kindergarten Individual Development Survey." At least half of states administer or are developing kindergarten entry assessments. In fall 2017 the Illinois State Board of Education began requiring teachers to report data on every child's skills at kindergarten entry using the Kindergarten Individual Development Survey. State and local stakeholders have asked for more information on the reliability and validity of the survey and on the gaps in children's skills at school entry. This study analyzed the psychometric properties of the 14 required items on the survey after its first statewide administration. It examined average skills and the variation in skill levels at kindergarten entry, as well as their differences across child subgroups and school poverty levels. And it interviewed teachers and principals about barriers in administering the survey and suggestions for improvement. Appendixes in this report include: (1) About the Kindergarten Individual Development Survey; (2) Methods; and (3) Supporting analyses. [For the report, see ED599357; for the brief, see ED599364; and for the snapshot, see ED599366.]