Lexia® LETRS® Efficacy Research 2025

Lexia® LETRS® (Language Essentials for Teachers of Reading and Spelling) teaches educators the skills needed to master the fundamentals of reading instruction—phonological awareness, phonics, fluency, vocabulary, comprehension, writing, and language. Educators who complete LETRS gain the deep knowledge needed to be literacy and language experts in the science of reading. Lexia® is dedicated to conducting rigorous scientific research to demonstrate the efficacy of its programs. This document summarizes 21 research studies that provide an evidence base establishing the efficacy of LETRS. Included are four peer-reviewed publications, seven evaluations conducted by external researchers, eight doctoral dissertations, and two internal research briefs. 

Of these studies, three meet the second-highest tier of evidence for an educational intervention described by the Every Student Succeeds Act (ESSA). The studies summarized in this report provide an evidence base establishing the efficacy of LETRS. Studies about LETRS First and Second editions are included, together with more recent studies about LETRS Third Edition. Studies about earlier editions demonstrate a rationale that LETRS Third Edition would be effective for teachers and students. Though research about LETRS Third Edition is limited, the weight of empirical evidence suggests it can improve teacher knowledge and instruction when used as intended. 

Download a copy for detailed information about each study, including a link to the original publication.