Young people are heavy users of social media, and social media play a central role in young adults’ drinking cultures and practices. Social media are replete with positive references to alcohol, which are positively associated with alcohol use. Yet social media have also been linked to recent declines in youth drinking seen in high-income countries. Alcohol marketing on these platforms is interactive, engaging, and dynamic. This chapter briefly overviews some key developments in research on social media and drinking cultures in young adults, and considers three contemporary technological developments: (1) the rapid growth of a mobile social media ecology with diverse and differentiated platforms; (2) alcohol marketing on data-driven and algorithmic platforms; and (3) evolving media automation, which means that users generate data that continually intersects with recursive, automatic algorithmic decision making. We conclude by considering what these shifts mean for alcohol researchers and those working in health promotion and alcohol policy, and the unique challenges they pose.