The differences between aggressiveness and assertiveness were examined using the Interpersonal Behavior Survey (IBS), a 136-item self-report questionnaire which was developed to distinguish between assertive and aggressive behaviors. Item level factor analysis was used in scale construction. Results indicated that: (1) the correlation between the aggressiveness scale and the assertiveness scale was -.05 in a sample of 402 community residents; (2) no substantial correlations existed between these scales in studies of over 30 groups; and (3) correlations of IBS scales with scales on seven personality inventories supported the discriminant validity of the assertion and aggression scales. (Author)