In order to solve the problem, in the case of a trailer coupling comprising a ball neck supporting a coupling ball, and also comprising a socket receptacle for a socket for the power supply of units acting on the coupling ball, the socket having a socket housing with a housing sleeve, which is provided with an insertion opening, and the insertion opening being closable by a cover that is mounted pivotably on the housing sleeve, of being able to mount the sockets as conveniently and easily as possible, it is proposed that the socket receptacle has a receiving channel, into which the housing sleeve extends starting from a first side of the socket receptacle, that the housing sleeve bears against the first side of the socket receptacle via a bearing surface, and that the housing sleeve is fixed to the socket receptacle by a retaining element, which is fitted starting from a second side of the socket receptacle and which is supported on the socket receptacle and is connected to the housing sleeve by a latched connection.