The Philadelphia City Schools engaged in a four-year program to develop and test dual audio television, a way to help children learn more from the massive amount of time they spend watching commercial television. The format consisted of an instructional radio broadcast that accompanied popular television shows and attempted to clarify and amplify the vocabulary and word concepts that were introduced. Using such a format for the "Flintstones" program, a study attempted to find the degree to which students could be encouraged to listen to the radio supplement, and the degree to which the special broadcast increased vocabulary learning. Results showed that differences in encouragement made only very slight differences in the rate of listening and that listening did not account for a significant portion of the variation in students' vocabulary improvement. (EMH)