Abstract: An article of footwear including a sole assembly with a bottom surface adapted to extend only to a medial portion of a user's foot is provided. An upper portion of the article of footwear includes a periphery that is partially secured to the sole assembly. The upper portion and the sole assembly define a cavity that is adapted to receive a portion of the user's foot which leaves the heel of the user's foot unsupported by the sole assembly. The cavity has a length and a width, with the width being at least 65% of the length. An attachment assembly is secured to the sole assembly.