This TCRP Digest provides the interim results of TCRP Project A-4, Electronic On-Vehicle Passenger Information Displays (Visual and Audible). The project explores ways in which transit agencies and transit users can benefit from on-board audio and visual display technologies. The major focus of this project is on the information needs of passengers while on board transit vehicles. This Digest summarizes passenger information needs, agency concerns, and the current and emerging display technologies. It is organized as follows: Introduction; Needs Assessment; Synthesis of Technologies; Conclusions; and Future Research.