The World Health Organization (WHO) 2006 weight-for-length (WFL) or BMI growth charts are now recommended as the new standard for children under 24 months. The objective of this study was to examine associations of ever being overweight during 1-24 months, based on the older Centers for Disease Control and Prevention (CDC) and WHO cutpoints, with risk of obesity at age 5 years. From well-child visits to a Massachusetts multi-site group practice during 1980-2008, we studied 15,488 children with length/height and weight measurements at 1, 6, 12, 18, and 24 months, and at 5 years. The main exposures were ever being overweight during 1-24 months using each of three cutpoints: CDC WFL ≥ 95th percentile, WHO WFL or BMI ≥ 97.7th percentile. The main outcome was obesity at 5 years (CDC BMI ≥ 95th percentile). We calculated multivariable odds ratios (ORs), adjusted for age, sex, race/ethnicity, and year. At 5 years, 10.8% of participants were obese. During 1-24 months, 21.3, 18.3, and 20.2% were ever overweight using CDC WFL, WHO WFL, and WHO BMI cutpoints, respectively. ORs (95% confidence interval (CI)) for associations of ever being overweight during 1-24 months with obesity at 5 years were 6.0 (5.4, 6.6), 6.3 (5.7, 7.0), and 6.0 (5.4, 6.7), respectively. Ever being overweight in the first 2 years of life is a strong predictor of obesity at 5 years. CDC WFL, WHO WFL, and WHO BMI cutpoints for overweight in early childhood provided similar estimates of later obesity risk.