Penis envy (German: Penisneid) is a stage theorized by Sigmund Freud regarding female psychosexual development, in which young girls experience anxiety upon realization that they do not have a penis. Freud considered this realization a defining moment in a series of transitions toward a mature female sexuality and gender identity. In Freudian theory, the penis envy stage begins the transition from an attachment to the mother to competition with the mother for the attention, recognition and affection of the father. The parallel reaction of a boy's realization that women do not have a penis is castration anxiety.
Freud's theories regarding psychosexual development, and in particular the phallic stage, were criticized and refined by other psychoanalysts, such as Karen Horney, Otto Fenichel, Ernest Jones, Erik Erikson, Jean Piaget, Juliet Mitchell, and Clara Thompson.