Children's savings accounts (CSAs) have emerged as a promising intervention to improve educational outcomes, curtail rising student loan debt, and promote equality of opportunity. Numerous localized CSA programs have emerged in the last decade, and many are embedded within school systems. This study leverages novel data to investigate participation in one of the oldest and most well‐known CSA programs in the country: the San Francisco Kindergarten to College (K2C) Program in the San Francisco Unified School District. Spatial analysis of 21,617 accounts at 74 elementary schools reveals statistically significant differences in the rates of elementary schools' K2C account participation based on the concentrations of banks, credit unions, and alternative financial service providers—net controls for neighborhood demographics. Unless explicitly addressed, substantial variations in the financial service environment across neighborhoods could undermine participation in school‐based CSA programs for the very children these programs intend to support.