Very few studies have directly compared reading acquisition across different orthographies. The authors examined the concurrent and longitudinal predictors of word decoding and reading fluency in children learning to read in an orthographically inconsistent language (English) and in an orthographically consistent language (Greek). One hundred ten English-speaking children and 70 Greek-speaking children attending Grade 1 were examined in measures of phonological awareness, phonological memory, rapid naming speed, orthographic processing, word decoding, and reading fluency. The same children were reassessed on word decoding and reading fluency measures when they were in Grade 2. The results of structural equation modeling indicated that both phonological and orthographic processing contributed uniquely to reading ability in Grades 1 and 2. However, the importance of these predictors was different in the two languages, particularly with respect to their effect on word decoding. The authors argue that the orthography that children are learning to read is an important factor that needs to be taken into account when models of reading development are being generalized across languages. (Contains 4 figures and 4 tables.)