We compared the sensory and motor behaviors of typically developing infants with those of infant siblings of children with autism spectrum disorders (ASD), who are considered high risk for the disorder, to explore potential sensory and motor markers for use in early diagnosis of ASD. We compared frequencies of sensory and motor behaviors during 10-min, videotaped, infant–mother play sessions and during 5 min of spoon-feeding between groups of 12-mo-old infants. Data from standardized measures of development, sensory processing, and behaviors commonly associated with ASD were also analyzed descriptively for the high-risk group. The results indicated that high-risk infants demonstrated fewer movement transitions (t  = −2.4, p = .03) and less object manipulation (t  = −2.4, p = .03) than low-risk infants. The sensory and motor differences found between typical and high-risk infants suggest that early screenings for ASD should include the examination of sensory and motor behaviors.