It is now a part of conventional wisdom that both China and India are emerging economic, political and even military powers in the 21st century. Terms such as “BRIC” and “Chindia,” and phrases such as “not China or India, but China and India” have entered popular discourse and policy discussions. Such terms imply a synergistic relationship between China and India—an implication that belies the tension that has characterized Sino-Indian relations for centuries. My view is less sanguine than many others’ about the prospects of their relations. Relations between the two countries will be fraught with difficulties and will likely remain fragile. Conflict and competitiveness are deeply rooted in historical and structural causes, while forces for harmony are more contingent on political will, cultural understanding and careful policy management. There are several areas in which their relations can go wrong. At a fundamental level, the two countries are in an economically competitive, not a complementary, relationship with each other. Their economic and social endowments are similar (as compared with China/U.S. or India/U.S.). India and China offer very different lessons about economic policies and growth. This is not to suggest that the two countries are headed toward an inevitable collision, but to identify the urgency of carefully managing their relations and nurturing trust and goodwill on both sides.