Abstract: A modular playpen for infants and young children comprising five basic parts including a plurality of substantially rectangular side panels; a plurality of vertical uprights slidably affixed to each end of a side panel via a longitudinal groove running the length of each vertical upright, thereby forming an enclosure; floor pads positioned within the enclosure; a series of horizontal cross bars removably engaged to the lower portion of each vertical upright thereby providing support to the playpen; and a central post positioned beneath the floor pads to provide additional support to the floor pads. The modular playpen can be reconfigured in a variety of shapes to conform to space constraints, and can be assembled, disassembled and reassembled again quickly without the use of tools.