A thin film transistor (TFT) including a polycrystalline active layer and a method for making the same are disclosed. An amorphous silicon layer is deposited on a substrate and is crystallized by using MJLC (metal induced lateral crystallization) to provide a poly-silicon active layer of the TFT. Specifically, the amorphous silicon layer is poly-crystallized during a thermal treatment of the active layer. The thermal treatment causes the MILC of the active layer propagating from portions of the source and the drain regions on which MILC source metal is formed through the contact holes of the TFT.