In 2013-14, Letterland had strong implementation, with moderate to high fidelity within approximately 90% of Wake County Public School System (WCPSS) K-1 classrooms. The impact of Letterland on students' reading achievement was neutral to positive. A significantly higher percentage of WCPSS kindergarten students were at or above benchmark mid-year on Phoneme Segmentation Fluency (PSF) and Nonsense Word Fluency-Correct Letter Sounds (NWF-CLS) than matched students from a comparison school district. WCPSS students' scores remained significantly higher on the end-of-year NWF-CLS. Participation in Letterland had a significant positive effect for limited English proficient (LEP), Asian, Black, and Hispanic /Latino kindergarten students varying by indicator and benchmark period. The percentage of kindergarten students with an end-of-year PSF score at or above benchmark increased 8.2 percentage points from 2011-12 to 2013-14. Results for NWF-CLS were inconsistent across years. Results suggest Letterland is a promising approach and should be continued. The following are appended: (1) Letterland Lesson Checklist; (2) 2013-14 Letterland Average Fidelity of Implementation Scores by School; (3) Average Students' Score on Key Kindergarten Literacy Indicators by Average Fidelity Score; (4) Propensity Score Matching Technique; (5) Tables and Figures of Percentage of Kindergarten Students Meeting Benchmark; and (6) Letterland Logic Model, 2011-12 to 2015-16.