WICAT Systems, Inc., produced a "proof of concept" instructional videodisc in college biology with support from the National Science Foundation. The project involved simultaneous development of content design, instructional strategies, software, and hardware, with a principal focus on evaluation of the instructional videodisc in the classroom. Videodisc development proceeded through three phases of increasing sophistication and evaluations were performed at each phase, including several comparisons of student learning with videodisc instruction and traditional lecture learning which were conducted at three different colleges. Results indicate that videodisc students consistently displayed greater learning and retention gains, reduced study times, and higher productivity ratios. This paper describes the evolutionary stages of development of the intelligent videodisc, "Development of Living Things," and the parallel evaluation studies. It also includes a discussion of instructional theory and its implications for machine-mediated learning. Ten data tables and a list of references are provided. (JB)