In this Sweet Sixteen story Mary- Kate and Ashley are put to the test when they swap places with their best friends. The number 1 brand for tweenage girls, Mary- Kate and Ashley are once again entertaining girls in their latest Sweet Sixteen series. But can the girls deal with the changes and without each other?

What would happen if your best friend became your sister? Mary-Kate and Ashley are about to find out when their friends, Brittany and Melanie challenge the sisters to spend a week in their shoes. Babies are cute, but can Mary-Kate handle the responsibilities of having a little brother, dirty diapers and all?

Ashley is thrilled to hang out with Melanie's supercool fashion-designer dad, but she's about to find out just how strange daily life without her sister can be.

This book features in the following series: Mary Kate And Ashley, Sweet 16, Sweet Sixteen .

There are 128 pages in this book. This book was published 2006 by HarperCollins Publishers .

Mary-Kate and Ashley Olsen have been huge international stars since the age of nine months, when they shared the role of Michelle in the sit-com `Full House'. With videos, video games, CDs, dolls, books, a fashion line and a magazine under their belts, their market impact is phenomenal.