Abstract: The design and implementation of a data-collection system for mobile phone-based research is described. This system is called MIDAS (for “Mobile Input Database Access System”) and uses computer and mobile phone technologies to replace traditional paper-based research instruments. The system is designed to be flexible to help researchers update, modify, and maintain the system with minimal technical skills. The system background and structure are presented in this paper. The system has passed beta testing and the results of preliminary testing are described. In the future, the researchers hope to add the ability to directly accept participants’ email messages and include automatic statistical analysis of collected data.