It seems that in the stores all the one-piece sleep and play jammies only go to 9 months. I usually buy a lot of DS's jammies at a local children's consignment store, but I'm afraid they won't have too many one-piece. I don't think DS is ready for the 2-piece sets that don't have footies. I found some online at carters.com but I really like my consignment store prices

Stop growing up baby boy!!!!
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Re: One-piece jammies in 12 month size are hard to find!
I found a few at the Carters store and Kohls.
I know Nordstrom carries a really nice blanket sleeper, but it is a little pricier
the lady at the Carters store said the 12 month ones always sell out really fast b/c people with little babies buy them up in the fall to get them through the winter.
A kiss he will never forget- Disney World 2014
Charlotte Ella 07.16.10
Emmeline Grace 03.27.13
Just looked those up and they look really nice!!! Thanks!
DD1 born 5/24/10.
Missed M/C at 14 wks Feb 2012.
DD2 born 5/14/13.
Missed M/C at 9 wks July 2015.
I just got some of the 'stretchies' from Children's Place online. We love them, they are definitely a favorite! Their size sections online are bit weird though. If you are shopping online, their newborn boy/girl section is sizes 0-3T and their baby is 6m-4T. You'll find the 1 piece stretchies in the newborn section.
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Here's a second vote for Children's Place. I love their cotton 'stretchies' and also the fleece blanket sleepers. They go up to the toddler sizes.
I also saw bigger sizes of jammies at Walmart.
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#3 : due 11.02.15