A variable valve timing system for an internal combustion engine, comprising a drive shaft driven by the engine, a camshaft driven by the drive shaft, and a cam supported by the camshaft for bearing against a valve actuating member. The camshaft and the drive shaft have parallel, spaced apart fixed axes of rotation, and are interconnected by a drive link, one end of which is coupled to the drive shaft and the other end of which is coupled to the camshaft. Means are provided for varying the spacing between an end of the link and the axis of rotation of the shaft to which that end is coupled. The system eliminates the need to move the axis of the central drive shaft, or to move an intermediate member or the camshaft, and also eliminates the need to have a control shaft external to the drive shaft or camshaft. The invention also provides camshaft assemblies and linkages for connecting camshafts and drive shafts.