Re: 15 month old not walking?
My DS always had low muscle tone in his legs (he never stood at all until 8 mos, and then for just a second at a time). His ped told us not to expect him to walk until 15-16 months. He ended up walking at 14 months, so we were very happy with that. But our ped told us that there's nothing to worry about until they hit 18 months, then then need an eval to see if it's a possible leg or muscle issue rather than a confidence and practice issue. It can't hurt to ask your ped to take a look next time you go in.
Kim - Wife to Brian, SAHM to Landon (11-21-06) and Lily (09-04-08)