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 .