Lock-out mechanisms for driver handheld computing devices. The lock-out mechanisms disable the ability of a handheld computing device to perform certain functions, such as texting, while one is driving. In one embodiment, a handheld computing device can provide a lock-out mechanism without requiring any modifications or additions to a vehicle by using a motion analyzer, a scenery analyzer and a lock-out mechanism. In other embodiments, the handheld computing device can provide a lock-out mechanism with modifications or additions to the vehicle, including the use of signals transmitted by the vehicle or by the vehicle key when engaged with the vehicle.