Jessica Simpson and Ashlee Simpson

Jessica Simpson is expanding her fashion empire to include a line for tweens.

Simpson and younger sister Ashlee have signed on to develop the collection, Women's Wear Daily reports, which will feature sportswear, denim jeans, leggings, shorts, hoodies, vests, graphic T-shirts, shrunken knits and drawstring-pants in sizes 7 to 16.

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"Creating a tween apparel collection was a natural extension for the brand. I'm excited to bring my sister, Ashlee, along as co-creative director of this division, because she brings a savvy rocker edge that defines today's tweens," Simpson said.

Simpson, whose brand includes apparel, cosmetics, sportswear and shoes, plans to have the new collection hit stores in the fall.