We got a load of 18-24 month hand-me-downs from a friend (yup, lots of Old Navy), and my 1 year old fits them now.  The weight thing is a good idea, except that my gal is also tall, so sometimes the clothes are the right fit around the belly, but don't cover the whole belly.  Plus, we mostly use cloth diapers (read: kid's butt looks huge) and we have some pants she can only wear with a disposable now.
