MMS (Multimedia Messaging Services) will become one of the most basic services of mobile communication as well as a promising m-commerce enabling service. In our study, we assumed that psychological traits are key determinants of behavioral intentions to employ pay-per-use information services, especially for MMS. Social cognitive theory and social influence theory are widely accepted, empirically validated models of an individual behavior. An empirical investigation of current MMS users in South Korea was conducted. PLS results provide strong support for the effects of credibility, relative advantage, and perceived ease of use on attitude toward MMS use intention. Specifically, all but one hypothesis linkage perceived costs to attitude were supported. The model provided a detailed account of the key forces underlying users' intention to adopt MMS including included both system and psychological traits measures that seemed to be highly relevant to the acceptance of MMS. Theoretical and practical implications of these findings are discussed in the paper.