My 4 month old son is a great napper at home but every sunday since he was born we have been spending most of the day at my parents house.  He always seems to get really over whelmed and does not nap there.  Any ideas on how to get him to nap there?  We have set up a little nursery in a quiet area but he still can't relax.

I have noticed the exact same thing with my 4 1/2 month old daughter. I just make sure I find a quiet, dark room and I bottlefeed and rock her to sleep. She fights until exhaustion and she never sleeps for a full hour like she does at home, usually only a half hour.