Within a relatively short time span, social media have transformed the way humans interact, leading many to wonder what, if any, implications this interactive revolution has had for people's emotional lives. Over the past 15 years, an explosion of research has examined this issue, generating countless studies and heated debate. Although early research generated inconclusive findings, several experiments have revealed small negative effects of social media use on well-being. These results mask, however, a deeper set of complexities. Accumulating evidence indicates that social media can enhance or diminish well-being depending on how people use them. Future research is needed to model these complexities using stronger methods to advance knowledge in this domain. The Puzzle: Does Social Media Impact Well-Being? Humanity had flirted with the idea of building a machine capable of spreading ideas quickly throughout the world for over 2000 years before all of the pieces necessary to do so finally came together for Johannes Gutenberg in the mid-1400s, while he was working on the shores of the Ill River in Strasburg [1]. It rested largely on Gutenberg's invention of a technique for pressing movable type (think of a scrabble set made of metal) against paper and ink to create a printed page [1] (https://www.britannica.com/biography/Johannes-Gutenberg). Prior to Gutenberg's invention, it would take up to 2 months to produce a single copy of a book. Now printers could produce 8000 copies during the same time [1]. Highlights Social media has revolutionized how humans interact, providing them with unprecedented opportunities to satisfy their social needs. An explosion of research has examined whether social media impacts wellbeing. First-and second-generation studies examining this issue yielded inconsistent results. An emerging set of third-generation experiments has begun to reveal small but significant negative effects of overall social media use on well-being. The results of these experiments mask the complexities characterizing the relationship between social media and wellbeing. Whether it enhances or diminishes well-being depends on how and why people use it, as well as who uses it. People use social media for different reasons (e.g., to manage impressions, to share emotions), which influence how it impacts their own and other people's well-being.