IT acceptance and post acceptance are central themes in IS research, and their related behaviors have been mostly investigated via reasoned and planned action theories, and are often portrayed as based on intentional and conscious decisions. This paper suggests an alternative, yet complementary perspective to the performance enhancing task-technology fit view of individual-IT interaction that has been predominant in IS research. To do so, we introduce the construct of IT Desirability to help better explain and predict individual post-adoption use beyond the influence of reasoned intentions, particularly in the context of hedonic every day IT, experiential computing, ICTs, social network sites and online communities. The paper first conceptualizes the construct of IT Desirability and assesses a theoretical model linking it to IS use. Next, a comparative study is presented where an affect-based model that integrates IT Desirability is compared to an established post acceptance model in the context of social network sites. The results of two online surveys of social network site users found that IT Desirability had a significant positive influence on IS use and helped increase the explained variance in the dependent variable beyond the influence of traditional models and constructs. The theoretical and practical implications of these results are discussed.