"Curiosity Corner" is an early childhood curriculum emphasizing children's language and literacy skills. It comprises two sets of 38 weekly thematic units, one for three-year-olds and one for four-year-olds. Program staff conduct daily lessons using sequential daily activities. The What Works Clearinghouse (WWC) reviewed three studies of "Curiosity Corner." One meets WWC evidence standards, and one meets WWC evidence standards with reservations. One study did not meet eligibility screens. The two studies included more than 500 preschool children from 34 preschools in Florida, Kansas, and New Jersey. Based on these two studies, the WWC considers the extent of evidence for "Curiosity Corner" to be medium to large for oral language and small for print knowledge, phonological processing, cognition, and math. No studies that meet WWC standards with or without reservations examined the effectiveness of "Curiosity Corner" in the early reading and writing domain. "Curiosity Corner" was found to have no discernible effects on oral language, print knowledge, phonological processing, cognition, and math. The following appendixes are included: (1) Study Characteristics; (2) Outcome Measures; (3) Summary of Study Findings; (4) Summary of Kindergarten Follow-Up Findings; (5) Ratings; and (6) Extent of Evidence by Domain. (Contains 9 footnotes and 22 tables.) [This report has been updated to include a review of two studies that have been released since 2006: (1) Preschool Curriculum Evaluation Research (PCER) Consortium. (2008). Chapter 5. "Curiosity Corner": Success for All Foundation. In "Effects of Preschool Curriculum Programs on School Readiness" (pp. 75-83). Washington, DC: National Center for Education Research, Institute of Education Sciences, U.S. Department of Education; and (2) Chambers, B., Chamberlain, A., Hurley, E. A., & Slavin, R. E. (2001). "Curiosity Corner: Enhancing preschoolers' language abilities through comprehensive reform." Paper presented at the Annual Meeting of the American Educational Research Association, Seattle, WA, April 2001. A complete list and disposition of all studies reviewed is provided in the references. For the 2007 edition of report, see ED497619.]