Stereoscopic image display devices and methods of driving the same. The display device is configurable to display 2D images in a 2D mode and multi-view images in a 3D mode, and includes an optical plate configured to pass through images in the 2D mode, and separate images in the 3D mode; a user detector configured to detect the number of users, and output detection data including the number of the users; a view mode controller configured to calculate the optimum number of views according to the number of the users, and select a view mode based on the number of the optimum views; and a multi-view images converter configured to output image data in the 2D mode without conversion, and convert the image data into multi-view image data for separation according to the number of the views in the selected view mode.