The history of a nine-year-old boy with a compulsive neurosis showed the prominent feature of a constitutional disposition toward hyperactivity. In infancy he developed rhythmical patterns to deal with a surplus of motor impulses. These were later elaborated into compulsive rituals. His hyperactivity and severe anxiety, re-enforced by early stressful experiences in regard to feeding, illnesses, sibling birth, and habit training, seemed to lead to premature ego and superego functioning. Parental apprehensiveness and contradictory expectations also contributed to his illness.