A ceramic matrix composite (CMC) turbine blade assembly includes a rotor, a CMC turbine blade, and at least one dovetail sleeve. The rotor has a blade slot with at least one slot surface. The slot surface is at a slot angle. The CMC turbine blade is received in the blade slot. The CMC turbine blade includes a dovetail root having at least one root surface. The root surface is at a root angle. The root angle is at least 5 degrees greater than the slot angle. The dovetail sleeve is received in the blade slot of the rotor. The dovetail sleeve has at least one inner surface contacting at least one root surface and at least one outer surface contacting at least one slot surface to radially retain the CMC turbine blade in the blade slot. A dovetail sleeve and a method of mounting a CMC turbine blade are also disclosed.