To examine the developmental trajectories of life satisfaction shown by adolescents during a major educational transition, 687 (327 girls, 360 boys) Finnish adolescents responded to measures of life satisfaction during the beginning of their last year in comprehensive school and three times annually thereafter during the transition to post-comprehensive education. Growth Mixture Modeling identified three latent groups based on life satisfaction: high-decreasing (18%), low-increasing (16%), and high-stable (66%). The results showed that boys and those with high academic achievement were overrepresented in the high-stable life satisfaction group. The results further showed that those with high school satisfaction at the last measurement time were more likely to belong to the high-stable or low-increasing life satisfaction group. Finally, adolescents in the high-stable life satisfaction group were more often on an academic track at the last measurement time.