An installation apparatus for handling a component of a wind turbine is provided. The installation apparatus includes a base, a support portion and an extensible arm having opposing ends connected to the support portion and the base, respectively. The extensible arm is adapted to move the support portion relative to the base and about a transverse axis of the installation apparatus between a transport position and an installation position. In the transport position the support portion rests on the base. In the installation position the support portion and the base form an angle. An assembly including such an installation apparatus and a method of mounting a wind turbine are also provided.