Approximately 72 percent of parents and 77 percent of youth reported exposure to one or more messages weekly through all media channels. Overall, there was substantial evidence of favorable campaign effects on four of five targeted parent beliefs and behaviors, including talking with their children about drugs, doing fun activities with their children, and beliefs about monitoring their children's behavior. There was little evidence of direct favorable campaign effects on youth, either for the marijuana and early intervention initiative or for the campaign as a whole. There were indications of an increase in past-month marijuana use between 2000 and 2002, followed by a decrease in both lifetime and past-month use between 2002 and 2004, but there was no evidence that the campaign was responsible for these changes. Among nonusing youth, there were favorable changes over time in antidrug attitudes and beliefs, as well as the proportion of youth saying they would definitely not try marijuana; however, results of the association analyses did not indicate that exposure to the campaign influenced these trends. The evaluation consisted of nine data-collection waves of the National Survey of Parents and Youth, an in-home survey designed to represent youth living in homes in the United States, as well as their parents. Each of the first three waves enrolled a nationally representative sample of youth ages 9 to 18 and their parents. The respondents at these waves represent the approximately 40 million youth and their parents who were the target audience for the campaign. Extensive tables and figures