"Ladders to Literacy" is a supplemental early literacy curriculum composed of 60 activities designed to develop children's print/book awareness, metalinguistic awareness, and oral language skills. The "Ladders to Literacy" activities can be implemented in a variety of early childhood settings and adapted for children with special needs. Although a "Ladders to Literacy" curriculum is also available for kindergarten students, this intervention report focuses on the preschool "Ladders to Literacy" supplemental early literacy curriculum. The What Works Clearinghouse (WWC) identified two studies of "Ladders to Literacy" that both fall within the scope of the Early Childhood Education topic area and meet WWC evidence standards. One study meets WWC evidence standards without reservations and one study meets WWC evidence standards with reservations, and together, they included 139 children in 26 preschool classrooms in southern New Hampshire. The WWC considers the extent of evidence for "Ladders to Literacy" on the school readiness of preschool children to be small for four outcome domains--oral language, print knowledge, phonological processing, and math. There were no studies that meet standards in early reading and writing, and cognition, so WWC does not report on the effectiveness of "Ladders to Literacy" for those domains in this intervention report. Appended are: (1) Research details for Russell, 2005; (2) Research details for PCER Consortium, 2008; (3) Outcome measures for each domain; (4) Findings included in the rating for the oral language domain; (5) Findings included in the rating for the print knowledge domain; (6) Findings included in the rating for the phonological processing domain; and (7) Findings included in the rating for the math domain. A glossary of terms is included. (Contains 8 tables and 8 endnotes.)