This study determined the prevalence of smoking stages in adolescents, the probability of transition across stages and the personal and environmental predictors of transition. A school-based study was conducted in 2010-11 using a random sample of 5197 students (mean age 15.7 years) in Tabriz city. The students were evaluated twice, 12-months apart. The latent transition analysis model revealed 9 interpretable statuses for the measurement of smoking stages. Prevalence data showed that at the first and second assessments 75.1% and 66.8% of students respectively were in the committer stage, while 4.8% and 7.1% respectively were daily smokers. Over 12 months, 10.1% of the never smokers became experimenters and 1.7% became regular smokers, while 17.0% of experimenters became regular smokers. The analysis also showed factors associated with transitions in cigarette smoking stages. Although the prevalence of smoking was low in our adolescents, the rate of becoming a smoker over 1 year was high.