Big Data is everywhere. Globally, billions of people use online platforms and digital devices to communicate, socialize, study, shop, and work. In the process, they generate a vast trove of digital footprints, documenting their thoughts, feelings, actions, and interactions. Social exchanges, for example, are captured in emails, instant messages, and social networking platforms. Expressions of attitudes and biases manifest in blog articles, online profiles, and social media posts. Online job markets and retail platforms capture our occupational and economic activities. Collaborative behaviors are traceable through corporate project management tools and massive multiplayer online games. Emotional states and well-being leave traces in language and digital images. Intimate attributes like sexual preferences and romantic choices are exposed on online dating sites. Moreover, even offline behaviors and social interactions are increasingly monitored by digital sensors in smartphones, wearable devices, smart buildings, and vehicles. These digital footprints of thought and behavior are commonly captured and recorded, creating extensive datasets widely referred to as Big Data. This chapter demonstrates that Big Data — characterized by its vast size, rapid accumulation, diversity, and complexity — is an invaluable resource for researchers interested in the human mind and behavior. Although not a silver bullet, Big Data presents an opportunity to overcome some of the significant challenges in social science research. When used correctly, it can provide new insights; enhance the diversity of research samples; assist in accessing under-researched populations; and yield more reliable, replicable, and ecologically valid results. Conversely, in the wrong hands, this data could be misused to invade privacy or manipulate the opinions of millions of people.