An apparatus (10) for helping to protect an occupant of a vehicle (12) that has a side structure (16) and a window opening (28) includes an inflatable vehicle occupant protection device (14) inflatable to a deployed condition in which the protection device is positioned between the side structure (16) and the vehicle occupant and covers at least a portion of the window opening (28). The protection device (14) when in the deployed condition has a first edge portion (70) connected to an adjacent portion of the vehicle and an opposite second edge portion (76) that is free from connections to vehicle portions adjacent the second edge portion. At least one tether (100) has a first end connected to the vehicle proximate to the first end portion (70) of the protection device (14) and an opposite second end connected to the second edge portion (76) of the protection device. The at least one tether (100) maintains the second edge portion (76) of the protection device (14) in the deployed condition and resists outboard movement of the second edge portion through the window opening (28) in response to occupant movement toward the window opening to restrain the occupant from ejection through the window opening.