Formed on an analysis of design practices, the behaviour chain model stipulates that social network designer's ultimate aim is to encourage users to adopt the social network site by entering a phase of true commitment. During this phase, social network users are driven to connect to known or unknown others by engaging in instrumental uses that create value and content and involve others, while staying active and loyal by investing time in the site. This paper investigates how designer's intentions, as captured by the behaviour chain model, materialise through users' reported practices in the social network site Facebook. A total of 423 Facebook users from 5 countries answered a questionnaire that allowed us to examine how 2 user characteristics, experience with the site, and culture, shape the nature of true commitment. Our findings show that experience with the site and even more so, culture, have an effect on users' motivations for using Facebook, as well as their instrumental uses and the time they invest on the site. This analysis reifies the behaviour chain model by allowing designers to understand how the features they design are embodied in users' practices.