Social networking sites and their functions are in constant change and with every new innovation different user behaviors are encouraged or prevented. Persuasive design is one way of designing a system to encourage a certain behavior. In this study we conducted four surveys of Sweden’s four most popular Social networking sites and how they are used. We followed up with ten interviews to gain understanding of why the users use these sites in a certain way. We identified four different target behaviors on Facebook, Instagram, Twitter and LinkedIn with help from the results we gathered from our surveys and our interviews. We then used a behavior model for persuasive design (FBM) to identify the different factors of the model in Facebook, Instagram, Twitter and LinkedIn’s design. The three factors of the behavior model are: motivation, ability and triggers. To gain further understanding of how Facebook, Instagram, Twitter and LinkedIn motivates, allows and triggers users to perform target behaviors we analyzed our findings using theories from research already done on persuasive design. We found that persuasive design was a powerful tool when it comes to making users perform a certain target behavior. Where the target behavior was not being performed we identified where the design did not correspond with the behavior model. Our goal was to expand on the behavior model by providing it with real world examples. By doing so we hope to help designers gain further understanding about how persuasive design works and how to put it into practice.