People born today will live for 68 years on average, 20 years longer than those born in 1950. By the mid-twentieth century, industrial countries had already made major strides in extending lifespans with improvements in sanitation, nutrition, and public health. After World War II, rapid gains in life expectancy in developing countries began to narrow the gap between these nations and industrial countries. Although average life expectancy worldwide continues to increase, gains have come more slowly in the last few decades. Worryingly, life expectancy has actually declined in some developing countries, while a few industrial countries have stalled or made slow progress on this important indicator of human health and well-being.