AOL instant messenger (IM) is a widely used Internet chat technology. There are indications that users do not find it easy to use initially, and this concerns AOL management; they think that if popular applications are not easy to use, the ability of AOL to attract and hold loyal customers will be impeded. In this chapter, the acceptance of IM technology is investigated within the familiar framework of the technology acceptance model (TAM), in which ease of use plays a pivotal role in promoting acceptance and subsequent use of a given technology. Computer self efficacy (CSE) is examined for possible antecedent roles in structural models of acceptance processes. It is determined that CSE does operate in a mediating relationship between some of the critical subcomponents of the TAM model but that it does not operate within the strictly defined theoretical boundaries established for general antecedents to the overall TAM process.