Depends on which M&P you get---seems to be 3 variants out there:
1. Mag disconnect and keyed internal lock
2. Mag disconnect and no internal lock
3. No safties at all other than the trigger safety and firing pin block---which are common to all models.
My M&P Compact 9mm falls into the third catagory.
They function pretty much like how a Glocks works---but feel better in the hand and have a slightly heavier trigger pull.
