In conversation, people regularly have to deal with problems of speaking, hearing and understanding. I report on a cross-linguistic investigation of other-initiated repair (a.k.a. collaborative repair, requests for clarification, or grounding sequences) in ten languages from five continents. Different languages make available a wide but remarkably similar range of linguistic resources for this function — from a simple interjection like 'huh?', which may well be a universal word, to more complex formats like candidate understandings, which present hypotheses for (dis)confirmation. The patterned variation points to several underlying concerns addressed by repair initiation: locating trouble, managing responsibility, and handling knowledge. As ever-present concerns, they provide the main degrees fo freedom within which the linguistic variation in the domain of repair plays out, accounting for the cross-linguistic similarities we find. As alternative selection principles, they provide people in interaction with flexible means for achieving mutual understanding, handling the distribution of knowledge, and managing social relations.