Patented is a disposable diaper with a front waist region, a back waist region and a crotch region between the waist regions. The diaper also includes an absorbent assembly with an interior surface, an exterior surface and laterally opposing longitudinally extending side flaps. Each side flap has longitudinally opposing ends and a longitudinally extending proximal edge. Each side flap is attached adjacent to its ends to the interior surface of the absorbent assembly and has a longitudinally extending elastic gathering member attached adjacent to its proximal edge such that when allowed to relax, the elastic gathering member contracts and lifts the proximal edge away from the interior surface of the absorbent assembly, thereby raising the side flap to form a side barrier. The absorbent assembly includes a lower covering sheet attached in a cruciform attachment pattern with a longitudinally extending portion and a laterally extending portion intersecting in the crotch region. The longitudinally extending portion has a smaller lateral extent than the laterally extending portion and the laterally extending portion has a smaller longitudinal extent than the longitudinally extending portion. Quadrantal portions of the lower covering sheet lying outside the cruciform attachment pattern are unrestrained by attachment to any other element of the absorbent assembly. At least one of the quadrantal portions of the lower covering sheet is laterally extensible. Two laterally opposing longitudinally extending backsheet strips are attached to the exterior surface of the lower covering sheet.