Thesis: Understanding human interactions and behavior in modern social contexts is a necessary condition, for the design of public policies to face the challenges induced by digital technology today and understand its functioning and impact on the society. The form that social influence takes and the way it operates rely on the technology or the medium used. Therefore, it is essential to include features of modern social networks in theoretical models and study the relevance of regulations of digital technology. This is precisely the goal pursued in this present dissertation. Chapter 1, joint with Francis Bloch, considers a targeting problem with peer effects where the identity of individuals is anonymized. Chapter 2 studies opinion formation in social networks, by taking into account the inequality of attention towards expressed opinions. Chapter 3, joint with Alexia Lochmann, models the behavior of individuals when cultural identity is at play and when individuals interact in two different contexts with their peers.