Using data from the first two waves of the High School and Beyond project, this study examines the reciprocal relationship between media use and academic achievement among American high school students. The hypothesis of the study was that TV influences achievement negatively as it displaces other, more beneficial activities, but that reading influences achievement positively, particularly reading skills. It was also hypothesized that achievement influences media use: specifically, achievement negatively influences television use and positively influences reading. The study used multiple regression in a cross-lagged model. No clear evidence of negative effects of TV on achievement were found. TV, however, was found to be relatively less beneficial than reading for pleasure. And while achievement's influence on the amount of TV viewing was not supported, reading achievement does seem to influence the amount reading.