Theories and descriptions of various infant fear behaviors are presented in this paper. Five examples of fear are given: (1) learned fear, in which the infant associates some unpleasant action with an agent, (2) unlearned fear, in which the infant experiences an intense sensory phenomena such as a loud noise, (3) stranger anxiety, (4) fear caused by a violation of the infant's expectancy, and (5) the child's fear of the loss of its mother. No specific behaviors have been found which are characteristic only of fear. Patterns of infant behavior can be interpreted as fear within the situational context in which the behavior occurs. Problems in the measurement of fear behavior, such as individual variability, the interpretation of stimulus meaning to infants, and the effect of prior experience are discussed. It is theorized that an infant's affective response is the result of a complex process involving the organism's status, cognition plans, and strategies, as well as the stimulus properties and the context of the situation. (BRT)