The proposed study represents a continuation of a successful NIH-funded research program on improving the effectiveness of mass media campaigns targeted toward individuals predisposed to high levels of sexual risk-taking. Our current project assessed the impact of a televised PSA intervention campaign designed specifically to reduce high-risk sexual behavior in young adults. Results have been impressive, with 4-6 month effects on condom use and critical mediators of condom use for high-sensation-seeking (HSS) and impulsive decision-making (IDM) young adults in an interrupted time-series, 2-city field experiment. The proposed continuation study will examine the effectiveness of intensive television campaigns in persuading young adolescents to delay initiation of sexual activity in 2 comparable top 125 Nielsen markets (Charleston, SC and Augusta, GA), employing a controlled time-series design similar to that in the current project. It will involve 3 high-saturation 3-month TV PSA campaigns (2 in 1 community and 1 in the other) focusing on delay of initiation of sexual activity, employing theory-based, age-appropriate, gender-targeted, and culturally sensitive messages. Over the 27-month assessment period, the study will monitor PSA exposure, sexual norms about waiting to have sex, refusal self-efficacy, involvement in a relationship, intentions to have sex and delay having sex, placing oneself in potentially sexual situations, as well as individual difference variables (particularly sensation-seeking and impulsive decision-making), through interviews with monthly random samples from a cohort of students in public schools in the 2 communities. An accompanying process study will provide insight into the individual and social processes through which the campaign has its effects on behavior. The principal objectives of the study are to: 1) test the ability of a targeted televised PSA campaign to reach at-risk adolescents with messages to reduce HIV-related risky behavior by delaying initiation of sexual activity, 2) provide a controlled test of the ability of such a campaign to produce significant changes over time in initiation of sexual activity and related mediating variables, 3) explore the roles of sensation-seeking and impulsive decision-making in moderating such effects, 4) explore how the processes through which the campaign affects the above mediating and outcome variables are similar or different for African-American and Caucasian adolescents, 5) explore the ability of a booster campaign to enhance or sustain the impact of a previous campaign, and 6) enhance understanding of the individual and social processes related to campaign effects. The potential public health significance of this project includes delaying sexual activity for hundreds of early adolescents, resulting in significant reductions in rates of unwanted teen pregnancy and STDs (including HIV) over an extended period of time. The televised public service announcements will also be made available to other communities for airing there, with potentially significant public health outcomes.