This paper describes the highlights of a review of both commercially available videodiscs and research prototypes that was undertaken for the Interactive Videodisc Project, and sets out design principles suggested by the best examples, which take advantage of the unique characteristics of laser videodisc technology. Design options on three levels of interactivity are considered, with emphasis on Level 1 (ordinary videodisc player, with a handset for play, still/step, scan, fast forward, and reverse), and Level 3 (player attached to an independent computer, with the computer controlling the player). Level 1 design options discussed include use of variable motion, forward and reverse, and use of audio tracks; the Level 3 design options discussed include simulations and databases. Finally, certain exemplary discs are described which have made the most of the medium by intermixing the various symbolic forms, allowing each to play the role for which it is best suited. A list of the 30 videodiscs that were reviewed is provided. (3 references) (EW)