The rapid pace of adoption of Web-enabled mobile handsets in worldwide markets has become an increasingly important issue for information systems professionals. A recent survey indicates that the number of global mobile Internet adopters is expected to reach nearly 600 million by 2008 (Ipsos-Insight, 2004; Probe Group, 2004), while the number of Internet-connected mobile phones will exceed the number of Internet-connected PCs by 2005 (The Economist, 2001). Such drastic convergence of the Internet and the mobile handset has been led by Asian and Scandinavian countries, where penetration has been especially meteoric. For example, roughly 70 million people in Japan, or 55% of the population, have signed up for mobile Internet access, in comparison to 12% in the United States (Faiola, 2004; Greenspan, 2003). Consequently, mobile phones or Keitai have been converted into devices for surfing the Internet, and by 2004 monthly mobile spending per consumer exceeded 35 euro. Much of this success can be traced back to 1999, when NTT DoCoMo introduced the “i-mode” service. i-mode is a mobile service offering continuous Internet access based on packet-switching technology (Barnes & Huff, 2003). Through an i-mode handset, users can access a main micro-browser, which offers such typical services as e-mail, data search, instant messaging, Internet, and “i-menu.” The “i-menu” acts as a mobile portal that leads to approximately 4,100 official and 50,000 unofficial sites (NTT DoCoMo 2003). Many such mobile portal sites can thus be considered as a pull-type advertising platform, where consumers can satisfy diverse information needs. Several researchers have attempted to conceptualize the success of i-mode in comparison to WAP (Baldi & Thaung 2002) and in the light of the technology acceptance model (TAM) (Barnes & Huff 2003). Okazaki (2004) examined factors influencing consumer adoption of the i-mode pull-type advertising platform. However, there is a dearth of empirical research in this area, and especially in developing a model that captures the specific dimensions of mobile Internet adoption. In this respect, this study aims to propose a measurement scale of consumer perceptions of mobile portal sites. The present study adopts, as its principal framework, the attitudinal model suggested by Dabholkar (1994). This includes “ease of use,” “fun,” and “performance” as important determinants of attitude. These are often referred to as “ease of use,” “usefulness,” and “enjoyment” in, for example, the TAM proposed by Davis (1986; Davis, Bagozzi, & Warshaw, 1989, 1992). The relevant literature suggests that dimensions similar to “ease of use” and “fun” are important antecedents of new technology adoption. For example, Shih (2004) and Szymanski and Hise (2000) found “perceived ease of use” and “convenient,” respectively, as important antecedents of online behavior. Likewise, Moon and Kim (2001) found “perceived playfulness” to be a factor influencing WWW usage behavior, similar to the “fun” dimension. However, unlike earlier studies of m-commerce adoption, this study drops the third dimension of the TAM, “usefulness,” in favor of “performance,” because the former is appropriate only for tangible products, but not relevant for technology-based services (Dabholkar & Bagozzi, 2002). In contrast, “performance” represents a dimension that encompasses the reliabilit y and accuracy of the technology-based service, as perceived by the consumer (Dabholkar, 1994). These three dimensions capture customer perceptions, which would initiate the attitude-intention- behavior causal chain (Davis, 1986).