Previous research has suggested that reading Arabic is slower than reading Hebrew or English, even among native Arabic readers. We tested the hypothesis that at least part of the difficulty in reading Arabic is due to the visual complexity of Arabic orthography. Third- and sixth-grade native readers of Arabic who were studying Hebrew in school were asked to detect a vowel diacritic in the context of Hebrew words and nonwords, Arabic words and nonwords (including connected and unconnected Arabic letters), and nonletter stimuli that resembled Arabic or Hebrew letters. Participants were better at detecting target vowels in Hebrew than in any of the Arabic conditions. Moreover, target detection in Arabic was better for letter strings containing connected letters than for those containing unconnected letters. The findings extend previous results on Hebrew versus Arabic reading and support a perceptual load account of the source of processing difficulty in reading Arabic. Performance in the Arabic conditions did not reveal a word superiority effect, suggesting that even by sixth grade, reading is not automatized to the point where it can compensate for the the visual complexity of the orthography.