The relationship between China and India ? the two fastest growing world powers ? is both complex and poorly understood. Despite their massive sizes, long histories, and rich cultures, interactions between China and India were limited until the mid-20th century, when the two countries found themselves neighbors. Despite testy relations for forty years, and a border conflict in 1962, China and India have proceeded to forge a productive commercial and diplomatic relationship in the 21st century, even if it is still marked by critical differences. A further complication for both parties is the role of other external actors, most notably the United States and Pakistan. Observers frequently tend to focus solely on the cooperative or competitive aspects of bilateral ties between China and India, but the key question today remains whether ? and how ? Beijing and New Delhi can overcome their contradictions over the coming decades.