Abstract: An inflatable construction set comprising a plurality of inflatable modular blocks in various shapes and sizes for easy construction of various structures is provided. Each inflatable modular block has substantially planar top and bottom surfaces and an attachment means on each of the top and bottom surfaces so that a plurality of inflatable modular blocks are capable of being stably stacked in any orientation. Preferably, each inflatable modular block has at least one interior rib inside the modular block to reinforce the structure of the substantially planar top and bottom surfaces of the modular block. An inflatable construction set in accordance with the present invention may further include various accessory modules such as inflatable doors, windows, turrets, roof system, and other construction components.