This study investigates the causal relationship between antecedents and consequences of social television viewing combining the television screen and concurrent use of a mobile, "second screen" media platform. The results indicate that social television viewing is a complex process driven by the viewers' program affinity, motives, interpersonal interaction, and the perceived media characteristics of alternative platforms. The social television viewing behavior also has a positive influence on loyalty to television programs, time-shifted viewing, and product purchase intention. The implications of these findings and recommendations for future research are discussed.