"Doors to Discovery"[TM] is an early childhood curriculum that uses thematic units to engage young children and support them as they build an understanding of their world. "Doors to Discovery"[TM] literacy activities are used to encourage children's development in a number of areas identified by research as the foundation for early literacy success: oral language, phonological awareness, concepts of print, alphabet knowledge, writing, and comprehension. One study of "Doors to Discovery"[TM] met the What Works Clearinghouse (WWC) evidence standards. This study included 76 classrooms in universal pre-kindergarten, Head Start, or Title I programs in the Houston, Texas, metropolitan area and examined intervention effects on children's oral language, print knowledge, and phonological processing. This report focuses on immediate posttest findings to determine the effectiveness of the intervention. The WWC considers the extent of evidence for "Doors to Discovery"[TM] to be small for oral language, print knowledge, and phonological processing. No studies that met WWC evidence standards with or without reservations addressed early reading/writing, cognition, or math. "Doors to Discovery"[TM] was found to have no discernible effects on oral language, print knowledge, and phonological processing. (Contains 9 footnotes.) [The following two studies are reviewed in this intervention report: (1) Assel, M. A., Landry, S. H., Swank, P. R., and Gunnewig, S. (2006). "An evaluation of curriculum, setting, and mentoring on the performance of children enrolled in pre-kindergarten." Reading and Writing. Retrieved March 23, 2007, from http://www.springerlink.com.bibliotheek.ehb.be/content/gx325u2h3612817r/fulltext.pdf; and (2) Christie, J., Roskos, K., Vukelich, C., and Han, M. (2003, June). "The effects of a well-designed literacy program on young children's language and literacy development." In F. Lamb-Parker, J. Hagen, R. Robinson, and H. Rhee (Eds.), "The first eight years--pathways to the future: Implications for research, policy, and practice" (pp. 447-448). Proceedings of the Head Start National Research Conference. New York: Mailman School of Public Health, Columbia University.]