A provocative description of the power of population change to create the conditions for societal transformation. As the world nears 8 billion people, the countries that have led the global order since World War II are becoming the most aged societies in human history. At the same time, the world’s poorest and least powerful countries are suffocating under an imbalance of population and resources. In 8 Billion and Counting, political demographer Jennifer D. Sciubba argues that the story of the twenty-first century is less a story about exponential population growth, as the previous century was, than it is a story about differential growth—marked by a stark divide between the world’s richest and poorest countries. Drawing from decades of research, policy experience, and teaching, Sciubba employs stories and statistics to explain how demographic trends, like age structure and ethnic composition, are crucial signposts for future violence and peace, repression and democracy, poverty and prosperity. Although we have a diverse global population, demographic trends often follow predictable patterns that can help professionals across the corporate, nonprofit, government, and military sectors understand the global strategic environment. Through the lenses of national security, global health, and economics, Sciubba demonstrates the pitfalls of taking population numbers at face value and extrapolating from there. Instead, she argues, we must look at the forces in a society that amplify demographic trends and the forces that dilute them, particularly political institutions, or the rules of the game. She shows that the most important skills in demographic analysis are naming and being aware of your preferences, rethinking assumptions, and asking the right questions. Provocative and engrossing, 8 Billion and Counting is required reading for business leaders, policy makers, and anyone eager to anticipate political, economic, and social risks and opportunities. A deeper understanding of fertility, mortality, and migration promises to point toward the investments we need to make today to shape the future we want tomorrow.