Gätjens I, Hasler M, di Giuseppe R, et al. - This study was undertaken to determine if the family environment and lifestyle factors act as mediators of the association between socioeconomic status (SES) and weight status in children and adolescents. Cross-sectional data from the Kiel Obesity Prevention Study of 4,772 girls and boys aged 5–16 is considered in mediation analyses. Fat mass (FM) was evaluated by bioelectrical impedance analysis and converted into a percent FM SD score (FM%-SDS). Data reported that the prevalence of overweight was 6.9%. The link between SES and FM%-SDS was entirely (5–7 and 9–11 years) and partly (13–16 years) mediated by comparable and age-specific mediators, including parental BMI, parental smoking habits, media consumption, physical activity, and shared meals. Overall, such factors resulted in a total mediating effect of 77.8% (5–7 years), 82.4% (9–11 years), and 70.6% (13–16 years). Consistent for both genders, the connection between SES and FM%-SDS was therefore mediated by parental weight status, risk-related behavior within families, and children’s and adolescents’ lifestyle factors. The family environment and lifestyle factors should also be addressed by interventions for obesity prevention, which are predominantly targeted at socially disadvantaged groups.