I have three boys my first talked at 9 months but didn't walk till 18 months, my second had words at 12 months and walked around 12 months,,, my didn't talk till 24 months and walked at 21 months. now none of them will stop talking or stop running! they are all just different. One Dr told me that sometimes if they develop early in one place they develop slower in another, which was how they explained my oldest, he could easily have a normal conversation at 15 months of age but couldn't walk at all (it used to freak people out how much he could talk) my second was fairly on target for development, and my third, well we were having out house built and had to be in an apartment for 6+ months (from 14-21 months for him) so it was crowded, he didn't need to walk, and there wasn't any room if he wanted to, we walked into the new house the first day (a big home twice the size of the apartment) and he walked clear across the living/dining room and never looked back, and has walked ever since. The Dr was worried about his walking but I just knew it would come when our situation changed (when we moved) ECI (early childhood intervention) is a good resource if you are concerned they can give you an evaluation and help determine a course of action, I was putting off calling them with my third till we got moved in to the new home, so I admit I was a bit lazy about it but my SIL used them with one of her kids and was very happy with their help, as is anyone else I've talked to. it can't hurt to get their help and guidance, but not walking at 16 1/2 months is not unheard of either, I think the range is up to 18 months for "normal" but my third has no problem walking at this point and he is 5yo and keeps up with the brothers easily.