Launched in 2012, The Big Lift is a collective impact initiative extending from preschool to third grade that aims to boost children's reading proficiency in San Mateo County, California, through four different types of activities, called "pillars": (1) High-Quality Preschool, (2) Summer Learning, (3) School Attendance, and (4) Family Engagement. RAND researchers are conducting a multiphase evaluation of the initiative, including an implementation study of the pillars and descriptive analysis focused on the outcomes of children who received Big Lift services. This report, the second in a series of descriptive analyses, follows up on the 2016-2017 kindergarten class by presenting data on their reading outcomes measured at the end of kindergarten and the start of first grade and describes the experiences and outcomes of the 2017-2018 kindergarten class measured at kindergarten entry. The authors determined that in the 2017-2018 kindergarten class, children who attended Big Lift preschool had higher scores than children who did not attend preschool, and children who attended two years of Big Lift preschool were more kindergarten-ready than children who attended just one year. Big Lift preschoolers had lower scores than children who attended other community programs. Evidence from the 2016-2017 kindergarten class suggests that the Big Lift advantage over children who did not attend preschool persisted into first grade. Results also indicate that children who attended the Big Lift Inspiring Summer program, children who went to other summer programs, and children who did not attend any summer program following kindergarten all had similar reading scores at the start of first grade. [This research was commissioned by The Big Lift with funding from the County of San Mateo. For the appendix to this report, see ED595041. For the related research brief, "The Big Lift Preschool, Two Years In: What Have We Learned so Far?," see ED594887.]