In this thesis, I investigate the use of spoken language interfaces by low literate users in the developing world, specifically health information access by community health workers in Pakistan. I present results from five user studies comparing a variety of information access interfaces for these users. I first present a comparison of audio and text comprehension by users of varying literacy levels and with diverse linguistic backgrounds. I also present a comparison of two telephony-based interfaces with different input modalities: touch-tone and speech. Based on these studies, I show that speech interfaces outperform equivalent touch-tone interfaces for both low literate and literate users, and that speech interfaces outperform text interfaces for low literate users. 
