['To examine how infant overweight and high subcutaneous fat relate to infant motor development.', 'Participants were from the Infant Care, Feeding, and Risk of Obesity Project, a prospective, longitudinal study of low-income African-American mother-infant dyads assessed from 3 to 18 months of age (836 observations on 217 infants). Exposures were overweight (weight-for-length z-score>or=90th percentile of 2000 Centers for Disease Control/National Center for Health Statistics growth reference) and high subcutaneous fat (sum of 3 skinfold measurements>90th percentile of our sample). Motor development was assessed by using the Bayley Scales of Infant Development-II. Developmental delay was characterized as a standardized Psychomotor Development Index score<85. Longitudinal models estimated developmental outcomes as functions of time-varying overweight and subcutaneous fat, controlling for age and sex. Alternate models tested concurrent and lagged relationships (earlier weight or subcutaneous fat predicting current motor development).', 'Motor delay was 1.80 times as likely in overweight infants compared with non-overweight infants (95% CI,1.09-2.97) and 2.32 times as likely in infants with high subcutaneous fat compared with infants with lower subcutaneous fat (95% CI, 1.26-4.29). High subcutaneous fat was also associated with delay in subsequent motor development (odds ratio, 2.27; 95% CI, 1.08-4.76).'] Is infant overweight associated with delayed motor development?