Joint ventures, a corporate form often compared to marriage, are back in the spotlight. In June, oil major BP shook the markets when it announced that it intended to exit its Russian joint venture, TNK-BP. By mid-July BP had started talks with its oligarch partners to discuss a sale. Such a divorce, which makes little business sense, will hardly be amicable, and BP’s experience with its Russian venture underlines on a grand scale the commercial and reputational hazards of entering into joint ventures in emerging markets. But for all the risks of such tie-ups, they are becoming increasingly important for many western multinationals.