"There is growing awareness that early motor signs may be a key component to early identification and interventions in autism spectrum disorders (ASD). To date, motor delays and/or differences in infants at high risk for ASD (HR) have been observed at 5 months of age, but not earlier. Despite the interest in identifying motor signs of ASD as early as possible, and earlier than currently observed at 5 months of age, the field is limited by the lack of sensitive and specific early motoric markers. In the Infant Neuromotor Control Laboratory, we are addressing these limitations by using wearable sensors to collect full days of spontaneous limb movement activity to measure motor control. By collecting data across multiple, typical, natural environment contexts we capture ecologically valid data. Our pilot data from 3 infants support that we may be able to detect differences in full-day leg movement patterns between infants at HR and infants with typical development (TD) at 3 months of age, however we need more data (as proposed here) to test this hypothesis. Given our pilot results and the known tendency toward repetitive behavior in ASD, we hypothesize that infants at HR will show lower movement rates and less variability in their leg movements than infants with TD. The results of this proposal would address a gap in accurate early identification of infants with ASD as early as 3 months of age, potentially allowing for targeted intervention to begin sooner. The results would provide necessary pilot data to allow power calculations to justify an adequately-powered federal grant proposal. Our next step would be to include wearable sensor data in a longitudinal study to determine the most accurate method for infant screening and diagnosis of ASD, addressing the crucial need for accurate, early diagnosis in ASD to support early intervention."