The law relating to state succession played a small but important role in the World Court's recent decision in Gabčíkovo-Nagymaros. Hungary's argument that the 1977 Treaty had not survived the transition from Czechoslovakia to Slovakia notwithstanding, the Court found that the 1977 Treaty had continued to be in force. Hungary presented several arguments relating to succession: the absence of consent; and that only certain rights and obligations (but not the Treaty itself) had survived. The present article analyzes these arguments in context and concludes that the Court came up with the right decision, but through a process of reasoning that is less than fully convincing.