This study utilized retrospective video analysis to distinguish sensory-motor patterns in infants with fragile X syndrome (FXS) (n=11) from other infants [i.e., autism (n=11), other developmental delay (n=10), typical (n=11)] at 9–12 months of age. Measures of development, autistic features, and FMRP were assessed at the time of entry into the study. Home videos collected from families were edited and coded with previously validated procedures. Findings revealed a pattern of sensory-motor features (e.g., repetitive leg movements, posturing, less sophistication/repetitive use of objects) associated with FXS, and suggest these infants were most similar to the group of infants with other developmental delays, irrespective of co-existing autistic symptoms later in life. Infant sensory-motor features in the FXS group were more predictive of an early developmental milestone (i.e., age walking) than later, more broad, developmental outcomes, or FMRP. Implications for early identification and differential diagnosis are discussed.