The morpho-syllabic Japanese writing system consists of the phonetic scripts of hiragana and katakana, the logographic kanji derived from Chinese characters and the less well researched romaji based on the Roman alphabet. In four experiments we investigated the speed with which Japanese college students read, named, and transcribed romaji as compared with hiragana. We examined these college students' proficiency in transcribing isolated words in Experiments 1 and 2, their oral reading speeds at the text level in Experiment 3, and naming latencies for syllables in Experiment 4. The results taken together showed that while transcription speed was almost comparable between romaji and hiragana, reading speed was much slower in romaji than in hiragana. It is suggested that this dissociation can arise mainly from differential reading and writing experiences in romaji among Japanese people. Both theoretical and practical implications are drawn for the future of romaji as the putative fourth script in the Japanese writing system.