Objective: To identify rates of overweight (body mass index [BMI] ≥85th percentile) and obesity (BMI ≥95th percentile) at 6-7 years of age and associated risk factors among extremely preterm infants born at <28 weeks of gestation. Study design: Anthropometrics, blood pressure, and active and sedentary activity levels were prospectively assessed. Three groups were compared, those with a BMI ≥85th percentile (overweight or obese for age, height, and sex) and ≥95th percentile (obese) vs <85th percentile. Multiple regression analyses estimated the relative risks of BMI ≥85th percentile and ≥95th percentile associated with perinatal and early childhood factors. Results: Of 388 children, 22% had a BMI of ≥85th percentile and 10% were obese. Children with obesity and overweight compared with normal weight children had higher body fat (subscapular skinfold and triceps skinfold >85th percentile), central fat (waist circumference >90th percentile), spent more time in sedentary activity (20.5 vs 18.2 vs 16.7 hours/week), and had either systolic and/or diastolic hypertension (24% vs 26% vs 14%), respectively. Postdischarge weight gain velocities from 36 weeks postmenstrual age to 18 months, and 18 months to 6-7 years were independently associated with a BMI of ≥85th percentile, whereas weight gain velocity from 18 months to 6-7 years was associated with obesity. Conclusions: One in 5 former extremely preterm infants is overweight or obese and has central obesity at early school age. Postdischarge weight gain velocities were associated with overweight and obesity. These findings suggest the obesity epidemic is spreading to the most extremely preterm infants. Trial registration: ClinicalTrials.gov: NCT00063063 and NCT0000.