Objectives: To examine the development and tracking of subcutaneous fat mass in the first 2 years of life and to examine which parental, fetal and postnatal characteristics are associated with subcutaneous fat mass. Design: This study was embedded in the Generation R Study, a prospective cohort study from early fetal life onward. Subcutaneous fat mass was measured by skinfold thickness (biceps, triceps, suprailiacal, subscapular) at the ages of 1.5, 6 and 24 months in 1012 children. Information about parental, fetal and postnatal growth characteristics was collected by physical and fetal ultrasound examinations and questionnaires. Results: Normal values of subcutaneous fat mass are presented. Total subcutaneous fat mass was higher in girls than in boys at the age of 24 months (P ¼ 0.01). Subjects in the lowest and highest quartiles at the age of 6 months tended to keep their position in the same quartile at the age of 24 months (odds ratios 1.86 (95% confidence interval (CI) 1.3, 2.7)) and 1.84 (95% CI: 1.3, 2.6), respectively). Maternal height and weight, paternal weight, fetal weight at 30 weeks, birth weight and weight at the age of 6 weeks were each inversely associated with subcutaneous fat mass at the age of 24 months after adjustment for current weight at 24 months. Conclusion: This study shows for the first time that subcutaneous fat mass tends to track in the first 2 years of life. Furthermore, the results suggest that an adverse fetal environment and growth are associated with increased subcutaneous fat mass at the age of 24 months. Further studies are needed to examine whether these associations persist in later life.