Once the metallic materials were subject to stress, a number of independent or alternative mechanisms may initiate and contribute to the deformation. As for the γ-TiAl-based alloys whose deformation kinetics is fairly complex, it is of particular significance to quantify the general constitutive relationship produced by each possible mechanism and identify the predominant mechanism at any specific loading conditions. For this purpose, in the present study Ashby-type deformation mechanism maps concerning six major deformation mechanisms have been constructed for various TiAl alloys with duplex (DP) and near-gamma (NG) microstructures. The general features as well as the effect of grain size on the appearance of the maps have been analyzed in detail. After a detailed discussion, it was believed that the proposed deformation mechanism maps were powerful tools in understanding the deformation mechanisms and predicting the deformation kinetics of DP/NG-TiAl alloys. Especially, they were demonstrated to be useful reference in alloy design and determination of proper processing parameters.