The cross-cultural and historical use of techniques of infant restraint, swaddling with or without the use of a board or cradle, are described. Such techniques were used very widely in temperate latitudes but have declined since the 18th century. Laboratory experiments indicate that swaddled babies sleep more, have reduced levels of motor activity in response to stimulation, fewer startles and lower heart-rate variability. No clear long-term effects of swaddling have been demonstrated. Results are reported of an ethological study of cradleboard use among Navajo Indians. Time on cradleboard declined from about 16 h a day in the first 3 mth to less than 9 h by the first birthday. The extent of cradleboard use was determined by both infant and parental actions. As compared with European infants, Navajo babies spend much more time in actual or potential social contact with adults. It is suggested that swaddling and cradleboard might be used in western cultures to reduce the social iolation of infants, to reduce parental child tension with 'sleep problem' babies and in various paediatric situations.