In this study, we investigated developmental aspects of eye movements during reading of three languages (English, German, and Finnish) that vary widely in their orthographic complexity and predictability. Grapheme-phoneme correspondence rules are rather complex in English and German but relatively simple in Finnish. Despite their differences in complexity, the rules in German and Finnish are highly predictable, whereas English has many exceptions. Comparing eye movement development in these three languages allows us to investigate whether orthographic complexity and predictability have separate effects on eye movement development. Three groups of children, matched on years of reading instruction, along with a group of proficient adult readers in each language were tested. All participants read stimulus materials that were carefully translated and back-translated across all three languages. The length and frequency of 48 target words were manipulated experimentally within the stimulus set. For children, word length effects were stronger in Finnish and German than in English. In addition, in English effects of word frequency were weaker and only present for short words. Generally, English children showed a qualitatively different reading pattern, while German and Finnish children's reading behavior was rather similar. These results indicate that the predictability of an orthographic system is more important than its complexity for children's reading development. Adults' reading behavior, in contrast, was remarkably similar across languages. Our results demonstrate that eye movements are sensitive to language-specific features in children's reading, but become more homogenous as reading skill matures.