I'll just paste something I had written for someone on another forum about it..
It is possible to have them together, but we try not to.
Reasons being:
Chickens like roosting, and can soil hay, feed, and water, and also poop on the goat itself.
Some goats don't like chickens and can actually hurt the chicken, one of our goats broke one of our hen's legs in half, although that was by accident I'm sure.. goats can get pretty heavy!
You can free range your chickens during the day and they will most likely enjoy the goats pen if they can get in.
Also - goats can get sick from chicken feed, most nonmedicated chicken feed is safe for goats, such as stratch grains etc, but its mainly the medicated stuff you need to watch out for, and vise versa.