The Big Lift™ (Big Lift) is a preschool-third-grade collective impact initiative in San Mateo County, California. The initiative is a partnership of the County of San Mateo, San Mateo County Office of Education, and the Silicon Valley Community Foundation. Launched in 2012, the initiative aims to boost children's reading proficiency by third grade through four different types of activities, called "pillars": (1) High-Quality Preschool; (2) Summer Learning; (3) Attendance; and (4) Family Engagement. The RAND Corporation is conducting a multiphase evaluation of the initiative, including an implementation study of the four pillars that underlie "Big Lift--The Big Lift Implementation Study: Final Report"--and a series of annual descriptive analyses focused on the outcomes of children who received Big Lift services. The first report, "Big Lift Participation and School Entry Indicators: Findings for the 2016-2017 Kindergarten Class" (see ED595013), focused on the early education experiences (prior to kindergarten entry) and kindergarten readiness of the 2016-2017 kindergarten class. This Technical Appendix provides details of data analyses described in the second report in the series of outcome studies, in which the authors follow up on the 2016-2017 kindergarten class by presenting data on their reading outcomes measured at the end of kindergarten and start of first grade. They also describe the experiences and outcomes of the 2017-2018 kindergarten class measured at kindergarten entry. [This research was commissioned by The Big Lift with funding from the County of San Mateo. For "The Big Lift Descriptive Analyses: Kindergarten Readiness and Elementary School Reading Outcomes for the 2016-2017 and 2017-2018 Kindergarten Classes," see ED595011.]