This longitudinal, year-long study compared sleep-wake state organization in two groups of infants-infants whose mothers abused substances during their pregnancies and nonexposed, typically developing, age-matched comparison infants-to determine whether differences in sleep-wake state organization existed between the two groups. Seventeen infants of mothers who were participating in a parent-infant residential treatment program for substance abuse were enrolled. Their sleep-wake state organization over the first year of life was compared to that of 17 age-matched comparison infants. The intent was to follow each infant on five occasions over the first year of life using established methods of time-lapse videosomnography to record sleep-wake state organization; however, attrition in the substance-abusing group was problematic. Some sleep-wake variables (i.e., Active Sleep%, Quiet Sleep%, Awake%, number of nighttime awakenings) were similar for both groups of infants at comparable ages across the first year. Total sleep time and the longest sustained sleep period (sleep continuity variables) differed significantly at some of the ages measured. Although overall sleep architecture appears highly resilient and well organized, some indications of sleep fragmentation and shortened nighttime sleep periods were observed in the substance-exposed infants. More research is needed to explain why sleep-continuity variables and not sleep-state proportion variables differed between the two groups.