I put my chicks outside at 6 weeks in a large dog cage at night (plastic variety with cage front) in the coop.  The older chickens were interested in them and wary of them, as well.  I let them out to free range under VERY CLOSE SUPERVISION the next day with the older hens and my rooster ( all of which are a year old).  The rooster was interested.  He did his "herding" thing to them like he does with his hens (stomping a foot and thrumming his wing), but stopped when he got next to them.  He just looked at them and then walked back to his older hens.  On the other hand, my chicken on the lowest pecking order (Delilah) acted more defensive.  She actually jumped on one and tore a chunk of feathers out.  I quickly gathered the chicks and put them in the run and shut them off from the older batch.  Just for the record, I have 7 hens and a rooster and 8 chicks (all pullets).  Anyway, I figured that I needed to let older group get used to the sight, smell, and...well, their presence before trying that again.  That was a week and 3 days ago.  I let them out again yesterday supervised.  The older group weren't interested except Delilah, who promptly tried having her way with them again.  The other chickens will even let them eat in the same area and are more tolerant of them before they get after them.  So, they will stay in the dog kennel in the coop until I feel better, and I will have to dedicate more time to sit out with them so they can free range with the older chickens before I leave them unattended.  
 
Just a note, my husband went to a chicken swap because a friend wanted layers without raising them, and he ran into a farmer friend who said that it was necessary to let them out with the older chickens so that they do establish a pecking order.  He said to keep an eye on them, but to let them go out together.  Also, he said that the chicks will have places to run for protection from the dominant hens.  He said that the new pecking order will have to be established anyway, and that it is unlikely that a chick will be killed.  
 
His words, not mine.  I do see logic in this, but I know that my Delilah is a mean little bugger!  
 
I hope this helps!  I think that I might try a version of this advice today...
 
Good luck
 
Cheers