I read an article this week on Baby Center about language and cognitive development for 15-month olds.  It says that most kids in this age group say a handful of words and it seemed to me that Sophie was saying a lot more.  So, today I kept track.  Granted, most of it isn't crystal clear and is most easily recognizable when in-person and in-context, but she can say a lot of stuff.  Here are the words she used today:

Food group: fries, pop, milk, drink, snack, cup

Her favorite things: blanket, baby, nuk (pronounced guk), teeth (loves to brush them), squirrel (loves to watch them), sock (loves to remove them)

People: Martin (pronounced "t"), momma, daddy, grandpa, grandma

Directives: yeah, no, down, more, gone (as in, it's gone, I want more), sit, kiss

Good manners: thank you (pronounced "ank oo"), cheese (as in preparing for a photo, not the food), good (as in my food is good)

And, most impressively, Sophie said her first full sentence today.  "No sit down."  That's our girl, independent right from the start.  And, obviously a genius.