Two primed naming experiments tested the orthographic depth hypothesis in skilled biliterate readers of Hindi and Urdu. These languages are very similar on the spoken level but differ greatly in script; Hindi is a highly transparent script, whereas Urdu is more opaque. It was accordingly hypothesized that form-based priming would be greater for Hindi than Urdu, reflecting greater reliance on a phonological assembly route in the more transparent Hindi script. Proficient Hindi/Urdu biliterate readers were presented with primes either in Hindi or Urdu script (Exp. 1), or in Roman transcription (Exp. 2), while targets were always in blocks of Hindi or Urdu. Across both experiments, form-based priming was observed only in Hindi. Additionally, target words were named significantly faster and better in Hindi than in Urdu. The results are taken as support for the hypothesis of differential reliance on phonological assembly as a function of script transparency. Further, the greater graphemic complexity of Urdu script relative to Hindi appears to have contributed to slower and less accurate overall single word reading for Urdu than Hindi, despite the fact that Urdu was the first learned script.