Autostereoscopic 3D displays represent a new technology, which is emerging into mobile devices. Yet, the user interface (UI) design in today’s mobile products, here especially mobile phones, relies on conventional interaction style, metaphors and UI layouts from 2D UIs. In this paper, we describe our design for mobile phonebook application with 3D UI for an autostereoscopic mobile device. Our process covers the comprehensive design cycle of charting end user perceptions, creating alternative concept designs, polishing the final design, SW implementation, and conducting a user study in the wild to evaluate the application.