In accordance with some embodiments, a computer-implemented method for use in conjunction with a device with a touch screen display is disclosed. In the method, at least a first portion of an electronic document is displayed at a first magnification. A gesture is detected on or near the touch screen display corresponding to a command to zoom in by a user-specified amount. In response to detecting the gesture, decreasing portions of the electronic document are displayed at increasing magnifications. If, upon detecting termination of the gesture, the magnification exceeds a predefined magnification, a respective portion of the electronic document is displayed at the predefined magnification.