A Smoking Prevention Interactive Experience (ASPIRE) is an innovative, computer-based smoking prevention and cessation intervention delivered to a culturally diverse population of high school students. Founded in the Transtheoretical Model of Change, five main and two "booster" sessions comprise the interactive intervention. Here we describe the intervention and the baseline characteristics from our study sample of 1,574 10th graders from 16 high schools in Houston, Texas. Environmental and behavioral smoking risk factors were assessed, and the two intervention groups were comparable with respect to most measured variables. The intervention program holds considerable promise in its ability to reduce smoking among teens.