My oldest is in 5th grade and we haven't had serious conversations about this yet but when we've had short conversations about it we lean toward getting one when they are away from the house more often and would need to call us for a ride or whatever. That's probably sometime between start of middle school and start of high school. The sports my kids are in have either me or a friend coaching. Most of the friends they play with live close enough and we're friends with their parents. My wife drives them to their music lessons and stays because it's far enough away that it's not worth going home between. I just don't see a need for it.