Our objective was to examine factors associated with compliance and support for a smoke-free campus before and after a 1995 campus-wide smoking ban for everyone, including teachers and visitors, in California. Adolescent (12-17 years) data from the 1993, 1996, 1999 and 2002 (N approximately 6000 each year) California Tobacco Surveys (population-based telephone surveys) were analyzed. Trends in compliance with smoke-free school policies and support for smoke-free campuses were examined among students in public and private schools. Perceived compliance with the no-smoking rule by most or all student smokers increased from 43.7 +/- 1.6% in 1993 to 71.5 +/- 1.4% in 2002. While non-smokers have overwhelmingly favored smoke-free school grounds since 1993 (more than 85% each survey year), support among current smokers increased from 55.8 +/- 4.7% in 1996 to 69.1 +/- 6.8% in 2002. Student smokers who saw teachers smoking in school were less likely to favor school smoking bans (odds ratio = 0.25, 95% confidence interval 0.12-0.49). The percentage of private school students seeing teachers smoke on school grounds has been at least twice that of public school students since 1996. Compliance with and support for smoke-free schools increased since smoking was banned on campus for everyone. Perceived compliance by teachers, much lower in private schools, appears to undermine student smokers' support of this policy. Increased efforts are necessary to communicate to teachers the importance of their modeling of policy compliance to students.