Self-serving biases in attribution have been widely explored; however, the effects of motivational factors on observers' causal attributions have been neglected in attribution research. To investigate these effects, observers' liking and perceived similarity toward a target person were manipulated. Subjects were 80 college students. The observer role was also manipulated, with subjects being either passive or active observers. Results showed that subjects insulted by a target person made significantly different attributions about the target person's behavior than non-insulted subjects. In addition, a significant interaction occurred between the insult conditions and the similarity conditions; attributions about the negative behavior of the target person were affected most by these motivational factors. Neutral behaviors were not affected. Observer role did not affect subjects' attributions as predicted. The findings have clinical relevance for therapists who need to be aware of the ways in which motivation and perceived similarity to clients may affect their causal attributions. (Author/JAC)