METHODS: School personnel (N = 7129) were recruited by cluster sampling from 60 junior high schools in Taiwan; of these, 5280 voluntarily returned self-administered, anonymous questionnaires (response rate = 74.06%) in 2004. RESULTS: Most personnel (70%) had advised students to quit smoking. School personnel who were older, male, responsible for teaching health, smokers, with positive attitude against tobacco, or with more knowledge of tobacco hazards were more likely to advise students to quit smoking. Personnel with more interest in and access to tobacco-related materials were more likely to advise students to quit smoking. Personnel who had received tobacco-prevention training were 2.41 times more likely to persuade students to quit smoking after adjusting for other factors. However, only half of the participants had ever had access to educational materials about tobacco use, and 8% had ever received training to prevent tobacco use. CONCLUSIONS: To reduce youth smoking prevalence, school tobacco-control programs should support tobacco-prevention training for school personnel.