San Francisco’s Kindergarten-to-College (K2C) is a Children’s Savings Account (CSA) program that provides a savings account to all kindergartners in the public school system to save for postsecondary education. This study is the first analysis of families’ contributions to the K2C accounts and how those contributions vary by student characteristic and school context. Following a review of existing research regarding college saving by American families in general and, specifically, by those participating in other CSA programs, this study examines contributions as one manifestation of families’ engagement with the K2C accounts. In addition, the study explores how the particular features of the K2C program manifest in asset accumulation and contribution activity, as well as how individual and school-level characteristics may influence observed interactions with the K2C accounts. This research provides insights into a CSA program that is the oldest and one of the largest in the country, and it offers lessons for policymakers and CSA administrators considering interventions to encourage college saving among families with school-age children.