† Actual dislocation of the hip, with the femoral head lying completely out of the acetabulum, seldom exists at birth. It develops as a gradual process that should be watched for throughout the first year of life in every child. The possibility of recognizing at birth the dysplastic hips that will progress to subsequent dislocation was investigated by (1) examining 3,500 newborn infants specifically for skeletal deformities and (2) securing pelvic roentgenograms from 150 unselected newborn infants for a study of normal dimensions, averages, and ranges. It was found that in the newborn infant the usual physical criteria (such as unilateral shortening of the extremity) for the diagnosis of congenial hip dysplasia are inadequate and unreliable and that discrepancies between the clinical and the x-ray findings (such as a high acetabular index) were distressingly frequent. Congenital hip dysplasia was diagnosed in 32 of the 3,500 infants. It is impossible as yet to tell which joints will become stable spontaneously, which will persist as subluxations, and which will progress to frank dislocations. Since the treatment is simple, it should be applied in all cases that suggest a hip dysplasia.