I'll fill in late teen a little more (applies to both sexes):

Sets own unique (and sometimes unobtainable) goals.
Takes religion seriously (either being for or against it or decidedly neutral).
Takes political stances.
Knows more than the rest of us!
Holds down a job, or dives into academics, or otherwise takes responsibility of family.

Different for different kids, but this is what I see.

Age 11-13: Squirelly phase. Goofy. Fun. In one ear and out the other. Honest. Can't see more than 30 seconds into the future. Can easily let go and be in the moment.

Age 13-15: Slacker phase. Peer pressure. Unsure of what and who they are. Will respond with coolness when in fact they are unsure of themselves. Afraid to ask for help. Making friends in the troop at this phase is crucial to getting them to stick through the whole program. Starting to like a challenge where failure is possible.

Age 15-17.5: Coalescing phase. Sometime in here they start becoming happy with themselves. Maturing. Becoming more dependable and responsible. Fun to work with. Fun to be with. Great for the troop.

Age 17.5-18: They get it. And then they're gone.

Great Responses and thoughts....

Anyone else?

I found that setting years and category limits to be too vague.

I found some 12 year old scouts more mature than 18 year old scouts. Heck, I've found some scouts more mature than their parents.

I'm thinking ages and stages don't always match up very well.

Stosh