Data from a 2-year study describe tobacco use trends, perceptions, and prevention effects for 1,281 5th and 6th graders enrolled in 12 randomly selected Washington State elementary schools. Youths were pretested, then randomly divided by school into skills, discussion, and control groups. Preventive intervention curriculums for the skills and discussion groups included age-relevant information on smoked and smokeless tobacco use, peer testimonials, debates, games, and homework. Youths in the skills group also learned communication and problem-solving methods for handling difficult situations around tobacco use. Following intervention, youths were posttested, then retested semiannually for 2 years. During the 2-year study, three-quarters of all smokers and nonusers and half of all smokeless tobacco users maintained their statuses. Only 10 percent of all smokers and 3 percent of all smokeless users quit their habits. One in six reported new tobacco use, one-third of smokers began using smokeless tobacco, and two-thirds of all smokeless users began smoking during the study. Most youths at final measurement perceived smokeless tobacco as less of a health risk than smoking. Nearly one in two of all smokeless users intended to smoke, and two-thirds were actually smoking at 24-month followup. Both smoked and smokeless tobacco use rates increased in all groups, and youths in the skills intervention group consistently showed the lowest rates relative to the other groups. These findings demonstrate the potential of skills intervention methods for lowering tobacco use rates among adolescents.