Drew did learn to walk first before he could stand on his own, but he was definitely standing up with help at that time. Using everyone's legs, reaching up for hands or pulling himself up on furniture was his means of standing up.
But now-a-days, as you watch the big/little guy, its amazing how easy he makes it look. It seems like he doesn't even have to think about it anymore.
There are times though that he may lose his balance because he's not thinking about, he just pops right up and wants to go, go, go. But if he falls (sometimes he can catch himself), he'll smile and get right back up and continue on his mission.