The dissertation examined the security and trust perceptions of users exposed to different user interfaces in two user interface design experiments. It looked at the impact of user interfaces that do not match exactly the look and feel of the native operating systems they function on (divergent user interfaces). It examined a program user's perception of sophistication, ease of use, usefulness, trust and risk when a user interface is graphically divergent versus when it is not. It also looked at the impact of security text on a user's perception of trust, expertise, credibility and security on an unfamiliar e-commerce web site user interface. This research hypothesized that security text caused persuasive effects on e-commerce users through the peripheral route of persuasion as described in Elaboration Likelihood Model theory. The results of two experiments indicated that there were no significant differences found in a program user's perception of trust, risk and download intention between graphically divergent and non-divergent interfaces. However, for divergent user interfaces, which contained familiar graphical imagery for a user, a positive software manufacturer trust effect was observed. The second experiment found that security text had no significant effect on a web site user's perception of credibility or security. But for those users who self-rated as Internet experts, it was found their perceptions of security were higher than those who self-rated as non-Internet experts.