Three studies of
Literacy Express that fall within the scope of the Early Childhood Education review protocol meet What Works Clearinghouse (WWC) evidence standards. The three studies include 1,004 preschool children from three to five years of age from 70 preschools in Florida and California.
Based on these three studies, the WWC considers the extent of evidence for Literacy Express on preschool children to be medium to large for oral language, print knowledge, and phonological
processing and small for cognition and math. No studies that meet WWC evidence standards with or without reservations examined the effectiveness of Literacy Express on preschool children in the early reading and writing domain.