Demographic and epidemiological changes are shifting the disease burden from communicable to noncommunicable diseases in lower-income countries. Within a generation, the share of disease burden attributed to noncommunicable diseases in some poor countries will exceed 80 percent, rivaling that of rich countries, but this burden is likely to affect much younger people in poorer countries. The health systems of lower-income countries are unprepared for this change. We examined the shift to noncommunicable diseases and estimated preparedness for the shift by ranking 172 nations using a health system capacity index for noncommunicable disease. We project that the countries with the greatest increases in the share of disease burden attributable to noncommunicable disease over the next twenty-five years will also be the least prepared for the change, as they ranked low on our capacity index and are expected to have the smallest increases in national health spending. National governments and donors must invest more in preparing the health systems of lower-income countries for the dramatic shift to noncommunicable diseases and in reducing modifiable noncommunicable disease risks.