As this physical maturity progresses, there is a dawning sex consciousness and the developing girl becomes shy, modest, retiring and introspective. She is very likely to be emotional and hysterical and to display a lack of stability and nervous control, which are not in accord with her usual temperament. A formerly dependable child may become capricious, erratic, and perplexingly inconsistent. One day she may be quite her normal, little-girl self and the next show inexplicably mature qualities. Or she may display a bewildering number of moods and fancies in the span of one short day. Too much cannot be said of the importance of wise supervision and guidance of the girl’s physical, mental and emotional life at this critical, emotional period. Many gynecological, obstetrical and neurological difficulties in her later life may be averted by her observance of sane rules of personal hygiene. Vigorous and regular out-of-door exercise; a simple, nourishing and well-balanced diet; adequate sleep in a well-ventilated room; regular bathing, and correction of any discoverable physical defects are the essentials. But of equal, if not greater, importance is an understanding and sympathetic oversight of the girl’s mental and emotional life, a steadying sort of comradeship. Her extreme sensitiveness and impressionability should be recognized and borne in mind, and every effort made to save her from strain and shock. Her nervous forces should be sedulously conserved by protecting her against experiences and diversions which would be unduly stimulating or irritating. Nor should demands be made upon her uncertain nervous endurance which she is able to meet only by great strain, if at all. It is important to her future poise and health that her confidence be courted, and when it is won, that all of her outpourings be received with a respect and seriousness commensurate with their great importance to her. Ridicule, and even unresponsiveness or indifference to her interests, may, and often do, result in a hurtful repression of one form or another. The logical consequence of such repression is an increasingly damaging neurosis later on in her life, capable of greatly impairing her health, happiness and usefulness. In short, all phases of the life of the adolescent girl should be made as wholesome, tranquil and free from stress and strain as is humanly possible. These comments upon the importance of mental hygiene at puberty may seem irrelevant to a discussion of obstetrical nursing. But the preparation of the entire female organism for its supreme function—that of child-bearing—is of concern to the obstetrical nurse, and should be understood by her. Moreover, every nurse is inevitably a health teacher, either by precept or example, or both. An awareness on her part of the maturing girl’s needs will fit her to help many perplexed mothers whom she meets along the way to a happy solution of this grave and vexing problem.