The content, and the phenomenal symbolic meaning to the subject, of posthypnotic suggestions may account for interindividual and intraindividual compliance with such suggestions. Before hypnotizing subjects, the authors measured their attitudes toward certain social issues and their beliefs and values as these related to the ascertained attitudes. After posthypnotic suggestion of change in these attitudes, measurement was made again. Experimental subjects changed attitudes and reorganized their beliefs significantly more than a control group. Several case reports illustrate two hypotheses about the nature of compliance with posthypnotic suggestion. According to the first hypothesis, such compliance is facilitated by the subject's being able to interpret the content of the posthypnotic suggestion in a manner consistent with the mechanism and affective reactions that, for him, characterized and maintained the hypnotic relationship. According to the second hypothesis, compliance is facilitated if that suggestion permits the subject safely to express and indulge a previously warded-off drive.