This paper describes a novel set of design principles and guidelines for
ensuring the immediate usability of public access systems. These principles and guidelines were formulated while developing PhotoFinder Kiosk, a community photo library. Attendees of CHI 2001 successfully used the tool to browse and annotate collections of photographs spanning 20 years of CHI and related conferences, producing a richly annotated photo history of the field of human-computer interaction. We used observations and log data to evaluate the tool and refine the guidelines. They provide specific guidance for practitioners, as well as a useful framework for additional research in public access interfaces. Keywords Photo collection, community photo library, group annotation, public access system, direct annotation, direct manipulation, drag-and-drop, immediate usability, zero-trial learning, walk-up-and-use, casual use. (UMIACS-TR-2001-71) (HCIL-TR-2001-23)