We make a case for treating a Web site as a social actor and propose para-social presence as a central construct to measure the structure of the relationship that evolves between a web site and its visitors. Para- social presence (PSP) captures the underlying psychological cues that measure the level and extent of interaction among participating social entities (in an online shopping context in this study). We also argue that one medium could possess different levels of PSP, depending on how it is configured and used. The first phase of our research conceptualizes and develops an instrument to measure PSP. The second phase investigates the impact of new technologies and associated web interface design decisions on perceived communication characteristics of a medium, PSP and subsequent user evaluations of the web site. Specifically, this research studies the impact of personalization technologies and support for virtual communities.