Yes!  This is all one dress!!  These long sleeve Autumn/Winter one-pieces, look like two - but they're deceptive!  Throw them on in one and you'll look like you've perfectly coordinated top and bottom halves!!  The ribbed tops are softly stretchy with a lovely flattering scoop neckline.  And the bottom is a contrasting, cotton gathered skirt.
 
Wear them with or without a belt to complete the look.  (Belts sold seperately and available in black, tan and grey.)  One sze.  Comfortably fits 8-16.