Whenever a new medium of communication becomes available to children, its effect on their well-being is debated. When motion pictures became popular, parents feared that seeing movies would degrade their children's conduct and morals. (In 1928, the Motion Picture Research Council invited a group of psychologists to measure the movies' effects on children. For results, see Charters, 1935.) More recently, television has come under similar scrutiny. People worry that television drama is too violent and sexual and that watching television robs children of time, imagination, and the ability to concentrate in school. Bad press about a medium's effect on children is one thing and evidence of harm often quite another. As researchers concerned with cognitive development, we wondered not so much whether learning from one medium was more beneficial than another, but rather whether children learn differently depending on the medium. And if so, how and why? Many researchers look at content to account for the important learning from a medium. Concern over television's displays of violent behavior generated many of the early studies with children. These studies documented that children do learn and sometimes perform aggressive behavior from observing television characters (Pearl, 1982). Children are likely to absorb considerable other content from television performances as well, including what to buy, what to wear, and how to behave in various social situations. Educational programs like Sesame Street have verified television's ability to teach academically relevant subject matter. (For discussion of early summative research, see Lesser, 1974.) Medium content is a fickle thing, however. It changes along with the tastes of its producers and audiences. Content also regularly crosses media boundaries: children's books are rewritten as screenplays, and television characters are licensed for use in print and other nonbroadcast formats. Important as medium content is, its impact on children's learning should not be exaggerated. Others who study media effects on children have focussed on how children use a medium like television. Most often documented (and decried)