This study investigates the relationships between Internet addiction and the areas of life satisfaction and positive or negative affects in Turkish adolescents. The research sample comprised 358 students studying in the sixth, seventh and eighth grades at four different middle schools in Canakkale city centre during the 2012-2013 academic year, of which 189 (52.8%) were females and 169 (48.2%) were males. Of the participants, 131 (37%) were sixth graders, 90 (25%) were seventh graders and 137 (38%) were eighth graders. The Internet Addiction Scale, the Multidimensional Student's Life Satisfaction Scale and the Scale of Positive and Negative Experience were used as data collection instruments in the study. Research data was analysed using Pearson's product-moment correlation technique and multiple linear regression. The results indicated that there was a significant negative correlation between Internet addiction and school and family satisfaction, and a significant positive relationship between Internet addiction and negative affects. The regression analysis results indicated that school satisfaction and negative affects are important predictors of Internet addiction. The results suggested that increasing adolescents' school satisfaction and developing their ability to regulate their emotions might be useful in decreasing Internet addiction. [Paper presented at the Annual Psychological Counselling and Guidance Congress (12th, Istanbul, Turkey, Sep 8-11, 2013).]