A new process developed in Puerto Rico makes reinforced concrete construction possible without the use of conventional forms and scaffolding. The method stresses simplicity to the exclusion of speed and it is perhaps best adapted to areas in which labor is cheap. First a double wall of ordinary hollow concrete block is laid up dry to any desired length and two courses high. Then plastic concrete, reinforced by wire mesh, is placed between the block walls. When the concrete has set two additional courses are added to the block walls and the process is repeated in this fashion until the poured wall reaches the desired height. When the final lift of poured concrete has set all the blocks are removed. Several advantages are claimed for the block forming system. It allows for more flexibility in both the height and the thickness of the poured wall, and it is thus well adapted to the construction of large industrial buildings, warehouses and machinery foundations.