"Let's Begin with the Letter People"[R] is an early childhood literacy curriculum that uses 26 thematic units--each of which covers a letter of the alphabet--to develop children's language and early literacy skills. A major focus of the program is phonological awareness, including rhyming, word play, alliteration, and segmentation. Children are encouraged to learn as individuals, in small groups, and in a whole-class environment. Teacher resource books and a set of classroom books and other program materials are available as a program kit. The What Works Clearinghouse (WWC) identified nine studies that investigated the effects of "Let's Begin with the Letter People"[R] on the school readiness of preschool children. The WWC reviewed four of those studies against group design evidence standards. Three studies (Assel, Landry, Swank, & Gunnewig, 2007; Fischel, Bracken, Fuchs-Eisenberg, Spira, Katz, & Shaller, 2007; and Preschool Curriculum Evaluation Research [PCER] Consortium, 2008, Chapter 6) are randomized controlled trials that meet WWC evidence standards with reservations. Those three studies are summarized in this report. One study does not meet WWC evidence standards. The remaining five studies do not meet WWC eligibility screens for review in this topic area. Appended are: (1) Research details for Assel et al. (2007); (2) Research details for Fischel et al., 2007; (3) Research details for PCER Consortium, 2008, Chapter 6; (4) Outcome measures for each domain; (5) Findings included in the rating for the oral language domain; (6) Findings included in the rating for the print knowledge domain; and (7) Findings included in the rating for the phonological processing domain. A glossary of terms is included. (Contains 8 tables and 17 endnotes.)