This research investigates the relationship of non-risk Turkish early adolescent urban middle school students’ need satisfaction, coping, mindfulness and awareness of consequences of online behaviours with problematic Internet use (PIU), and the effectiveness of a small scale preventive program on PIU in two studies. Study 1 examined the extent to which coping strategies in stressful situations and mindfulness during online engagement mediates the relationship between need satisfaction in real life and PIU, and the reliability of measures to assess coping, mindfulness, online persona, PIU and need satisfaction. A cross-sectional design and Path analysis on a sample of 165 Turkish early adolescents (Mage = 12.88, SD = .83; 49.1% females) found that need satisfaction was negatively related to PIU via low avoidant coping and high mindfulness in Internet engagement. Study 2 designed, implemented and tested the effectiveness in preventing PIU through a 10-week Mindful and Need-supportive Digital Life Responsibility Program (MiNDLifeResP) based on mindfulness in online engagement, awareness of responsible Internet use, satisfaction of psychological needs, and comprehensive understanding of active coping strategies. A quasi-experimental design collected both quantitative and qualitative data from twenty experimental group students (9 females) and twenty control group students (8 females). In pre-test, post-test and follow up, PIU, responsible Internet use, coping strategies, and psychological needs, plus frequencies and limitations in Internet use, were assessed. Post intervention interviews sought experimental group students’ experience and perceptions of the implemented program. The experimental group and researcher kept diaries during the intervention, and parents reported on their children’s Internet use behaviour in pre- and post-tests. For pre-test, post-test and follow-up descriptive statistics and bi-variate correlations were calculated, along with MANOVA for gender differences. In addition, a two-way repeated measures ANOVA and a cross tabulation analysis was used in the main analysis, a one-way repeated measure ANOVA for students’ quantitative diaries, and a paired-sample t-test to compare parents’ reports about their children’s time spent on Internet. An independent sample t-test compared students’ perception of need satisfaction in quantitative diaries. Content analysis was performed on experimental group students’ qualitative interview data, and on the researcher’s reflection diary. The MiNDLifeResP was unsuccessful in increasing RIU and decreasing PIU and avoidant coping for not-at-risk adolescents, but successful in forming positive cognitions for students regarding harmonious Internet use, active coping, and awareness of the present moment. Additionally, the need supportive component was successful for students’ need satisfaction during the intervention. Recommendations to improve the study and implications of the results for education and teaching practices are then discussed.