After years of slow and steady development, generative artificial intelligence (AI) technologies have exploded in popularity, and many experts believe that we are entering a new, AI-driven phase of the Industrial Revolution. The advent of AI as the new engine of growth raises questions about the future of labor. Some have expressed concerns that, in the short run and the medium run, AI may lead to employment losses brought about by task automation and the skill obsolescence of the current labor force. But an additional risk of AI is in the long run: Unlike previous technologies, AI may undermine labor’s share of national income, and technological innovation could, for the first time, permanently reduce the importance of labor in the economy, even if full employment is maintained. In this article, we discuss how technology affects labor’s share of income, why the labor share has been stable for so long, and why AI may threaten that stability.