The purpose of the study was to evaluate the effectiveness of "PAVEd for Success," comprehensive preliteracy program guidelines to support the development of foundational preliteracy skills in 4 year olds. Prekindergarten teachers received professional development on variables of the program that included a summer institute, after-school workshops, and classroom support from preliteracy specialists. Children were assessed at prekindergarten entry, following the implementation period and at the end of the school year. Vocabulary knowledge, phonological awareness, and alphabet knowledge were assessed during the prekindergarten year, and early literacy indicators and early decoding skills were assessed at the end of the kindergarten year. While all experimental variables showed some benefits to the development of children's preliteracy skills, only the full program benefited children who entered the prekindergarten program at risk for reading difficulties. The program participants benefited in early literacy and decoding skills when compared to controls. Implementation by teachers with support and sustainability of program features without support was also evaluated. Teachers were most likely to implement and sustain program features which shared consistency with some prior literacy focus and when they were able to integrate program features across the curriculum. This research suggests that long-term change in the literacy skills of young children will involve complex and multifaceted approaches to preliteracy development. (Contains 8 tables and 1 note.)