Ever so often Mattel releases a new little sister for Barbie. Sadly, I am old enough now that I remember welcoming all 4 of them. Over time, Mattel tweeks the dolls a bit. Like Barbie when introduced was originally a teen and she has been aged to an adult now. Skipper was originally a light blonde, now she's brunette. Stacie had a wider head and then next doll in the line was Kelly. When she was introduced she was a toddler named Kelly. I know because I bought the doll of her in a crib. Later, they aged her to about 6 yrs old to make room for Barbie's youngest infant sister, Krissy..eons later in 2010, Kelly grew two inches taller and was renamed Chelsea. Us 90's kids and beyond still call her Kelly because we grew up with that name and it's hard to adjust but also, I'm not calling her Chelsea because I think it was a dumb move by Mattel to up and rename her for no reason.