Regional Educational Laboratory Southwest partnered with the Arkansas Department of Education to examine Arkansas's middle school and high school indicators of postsecondary readiness and success, building on an earlier study of these indicators (Hester et al., 2021). Academic indicators include attaining proficiency on state academic examinations, grade point average, enrollment in advanced courses, and community service learning. Behavioral indicators include attendance, suspension, and expulsion. Using data on statewide grade 6 cohorts from 2008/09 and 2009/10, the study examined the percentages of students who attained the readiness and success indicators and the percentages of students who attained postsecondary readiness and success outcomes by gender, race/ethnicity, eligibility for the National School Lunch Program, English learner student status, disability status, age, and district locale. The study also examined whether the predictive accuracy, specificity, and strength of the indicators varied by these student groups. This document presents the following three appendixes that accompany the study: (1) Data and Methods; (2) Supporting analyses; and (3) Supplemental analyses. [For the full report, see ED624014.]