Emerging web applications and networking systems such as blogs have become popular, and they offer unique opportunities and environments for learners, especially for adolescent learners. This study attempts to explore the writing styles and genres used by adolescents in their blogs by employing content, factor, and cluster analyses. Factor analysis was used to identify the factors that influence the genres of adolescents' blogs, and cluster analysis was used to divide the adolescents' blogs into the topic balanced group and the expression of feelings group. The findings revealed that the two groups of adolescents showed a difference in blog background, genres, and use of Internet language variables. Additionally, female adolescent bloggers tended to post more articles than male bloggers. Furthermore, the number of posted articles between female and male adolescents varied in some genres. (Contains 11 tables and 1 figure.)