In 2018, the Chan Zuckerberg Initiative engaged the John W. Gardner Center for Youth and Their Communities at Stanford University (Gardner Center) to partner with public school districts in San Mateo County, CA to examine the barriers to educational success that homeless and highly mobile students face. Given the increasing prevalence of homelessness and unstable living arrangements among youth nation-wide, and particular challenges related to income inequality and rising housing costs in San Mateo County, this partnership aims to identify factors that may promote academic achievement among this vulnerable population. This report presents results for the first of three stages of this investigation into the prevalence and distribution of youth experiencing housing instability in San Mateo County, breaking the school districts into three geographically-based sub-groups. The first stage describes youth enrolled in the Sequoia Union High School District and its eight feeder elementary school districts. This report aims to address three key research questions: (1) What is the size and distribution of the homeless and highly mobile student population in Sequoia area school districts during the last three to five years? (2) To what degree do circumstances vary for this student population (e.g., in terms of chronicity of homelessness, instability of current living arrangements, placement in foster care, newcomer immigrant background, family structure)? and (3) How does being homeless or highly mobile affect students' educational outcomes?