The development of reading-related phonological processing abilities (PPA) represents an important developmental milestone in the process of learning to read. In this cross-sectional study, confirmatory factor analysis was used to examine the structure of PPA in 129 younger preschoolers (M = 40.88 months, SD = 4.65) and 304 older preschoolers (M = 56.49 months, SD = 5.31). A 2-factor model in which phonological awareness and phonological memory was represented by one factor and lexical access was represented by a second factor provided the best fit for both samples and was largely invariant across samples. Measures of vocabulary, cognitive abilities, and print knowledge were significantly correlated with both factors, but phonological awareness/memory had unique relations with word reading. Despite significant development of PPA across the preschool years and into kindergarten, these results show that the structure of these skills remains invariant.