When Mark McGwire broke Roger Maris's home run record in September of 1998, he was instantly declared an American hero and held up as a positive role model for teenagers and young adults. The extensive media attention focused on McGwire made the general public aware of his use of a muscle-building dietary supplement, Androstenedione. It also increased the public's awareness of McGwire's public service to prevent child abuse. The present research assesses audience involvement with McGwire through parasocial interaction and identification, and the effects of that involvement on audience knowledge of and attitudes toward Androstenedione and child abuse prevention. Results indicate parasocial interaction with an athlete regarded as a public role model likely leads to audience identification with that person, which in turn promotes certain attitudes and beliefs. In this case, parasocial interaction and identification with Mark McGwire was strongly associated with knowledge of Androstenedione, intended use of the supplement, and concern for child abuse. Implications of this research for featuring celebrities in health communication campaigns are discussed.