In cooperation with Stanford University's National Student Support Accelerator (NSSA), Chapter One studied its impact on student reading growth over four years. Nearly 800 kindergarten students in a large Southeast district were randomly assigned at the start of kindergarten to receive tutoring through third grade.

The treatment group received 1:1 high-impact tutoring during the school day from an Early Literacy Interventionist (ELI). Sessions were delivered in 5-10 minute short bursts to maximize student focus at their young age while minimizing classroom disruption. Students also received 10–15 minutes of independent practice each day on Chapter One's proprietary Student Platform, which reinforces the content they just learned with their ELI.

Key findings include:

• In Kindergarten, students were twice as likely to be reading on grade level than their non-participating peers (68% proficiency in treatment group, 32% in control group).

• In 1st grade, students showed a +0.35 standard deviation improvement on nationally-normed Oral Reading Fluency assessments.

• Students assigned to Chapter One scored 0.12 to 0.17 standard deviations higher on state-administered reading assessments across grades 1 through 3.

• Treatment students were less likely to have an IEP or be retained by the end of the study.