Head banging is a curious behavior pattern sometimes seen in infants and young children. This activity is characterized by repetitive movements marked by a definite rhythm and monotonous continuity. The head is struck rhythmically against the head board, side railing of the crib, or other objects. This is not a tantrum type of behavior but is marked by an almost compulsive repetitiveness. Characteristically, it appears to commence sometime in the last half of the first year and is usually preceded by other less dramatic rhythmic motor behavior such as head or body rolling and crib rocking. While this behavior has come to the attention of medical practitioners, very little in the way of descriptive material or controlled research has been done. Gesell states, "Rocking on hands and knees and bedshaking are common forms of deviation. Head banging and head rolling also have their origins in this period from 40 weeks to 21 months" (5, p. 308). Spock (i2) discusses this rhythmic behavior under the subheading of "Common Nervous Symptoms." Lourie (io) noted head banging in a study of 130 children who manifested a variety of rhythmic patterns. Other writers have noted this behavior, and references appear in medical, psychological and popular literature (i, 2, 4, 6, 7, 8, 9, 13)The purpose of this paper is to describe systematically head banging behavior of normal, not hospitalized young children. Specifically, this report describes the positions in which head banging takes place, the age of onset, the frequency and persistency, the tempo, and related factors. In addition, reaction to metronome stimulus and a follow-up study of behavioral patterns of a portion of the sample are described.' Thirty-three head bangers were observed under normal bedtime conditions; 23 were boys and Io were girls. The age range for the total group was from io to 49 months; average age was 26.6 months. All of the observations described in this report took place in the homes of the subjects. Twenty-six of the 33 subjects in this sample were obtained from referrals of practicing physicians in cities of upstate New York. Seven cases were found through personal contacts.