I have been trying to move my now almost 7 week old baby chicks (possibly all pullets - or so we hope ) in with my now 10 week old White Leghorns (4 roos, 1 pullet) since the babies were 4 weeks old. Here's how I did it: Week 1: Starting with when the chicks were 3 weeks old, I would put the babies into an exercise pen in the run with the WLs and then put the babies back in the house at night into their brooder. Week 2: Then when they were 4 weeks old I moved them outside to the right portion of the coop where they had essentially their own mini coop - it was protected from the WLs by chicken wire above and hardware cloth below the roost where the WLs hung out. During the day I took them from their side of the coop and put them into the exercise pen and left them there with food/water while the WLs were free to be in the run and freerange with supervision in the evenings. Week 3: Went on vacation - friend took care of chicks - babies were left in their side of coop and WLs were allowed into run only and not freeranged. Week 4: Let the babies out each day from their side into the run to mingle with the WLs - if things got intense I'd let the WLs out to freerange awhile and that gave the babies a chance to search into the main coop or run back into their side or just hang out without getting pecked. The WLs were allowed to come and go in the run while I was there, but they were put back into the run when I was done with cleaning/feeding time. The babies had been going into their side of the coop at night by themselves and huddling on the floor and the WLs have been roosting at night inside the main coop. Week 5: (this week) Last night I went to the coop after everyone was in bed. I moved the babies one by one into the main coop and put them in the door before it closed at 8:15pm. They chirped a bit, but settled down. The WLs were still awake but did not come down off the roost. This a.m. I went to check on everyone. The door had not opened yet so I have to figure out what I did to it last night to make it not auto open at 6a.m. - but the chicks were all fine. The WLs came down and stood around the food & water. The babies stood up and were the 1st ones out the door when I finally opened it. The babies came out down the plank and the last one promptly got a quick peck by the lead roo who comes out first usually. Then everyone went about their usual chicken duties and seemed fine. So I'm calling this successful! Of course tonight will be the key as I plan to leave the babies side closed and only let them into the main coop now. We'll see how that goes I will put the babies into the main coop today when I clean it out so that they know that's their new home and take away the ladder to the other side for now. Man this chicken stuff is alot more involved then I thought it would be - I figured they would all just get along...silly me!