A collapsible bottomless storage pen having a continuous articulated peripheral wall including parallel sidewalls and interconnecting end walls. Each end wall includes a bend line. Interior connecting flaps are hingedly attached to the end walls and cooperatively engage each other to retain the pen in an operative position. The end walls and connecting flaps are sized to permit folding of the pen to the length of the sidewalls, such that the connecting flaps and end walls are parallel to and between the parallel collapsed sidewalls.
