Based on past research indicating that the attitudes and behavior adopted during adolescence may determine the course of an individual’s health and well-being across his/her entire life span, adolescent smoking has been widely recognized as a health hazard. The present study examined the attributions given by Finnish adolescents for their smoking and for smoking by others. Specifically, using a 1984 cohort and a 1999 cohort, the study set out to determine what types of reasons were given by adolescents for their own cigarette smoking in 1984 and 1999, what kinds of reasons were perceived by adolescents for other people’s cigarette smoking in 1984 and 1999, if the attributions changed over this 15-year period and how, and how the participants’ gender and actual smoking habits related to the reasons given for smoking. The cohort in 1984 consisted of 396 adolescents age 14-16, and the 1999 cohort consisted of 488 adolescents age 14-16. In both studies, data were gathered using a questionnaire. The results indicate that the reasons given for one’s own smoking and for smoking by others changed in some important respects over 15 years. However, the attributions were only slightly related to the respondents’ gender or personal smoking habit. In respect to the participants’ own smoking, it appeared to be a shift from “belonging” types of reason to “feel good” types of reason. In respect to the smoking by others, the pattern was different, with attributions shifting from the addiction and habit reasons to the “belonging” types of response. Tables, references