A cellular confinement system for soil, sand or other filler material comprises a number of sub-assemblies each made up of a plurality of interconnected open cells of fabric material. The sub-assemblies are stackable one on top of the other to provide a structure having at least one generally vertical side or end wall. The system further comprises sealing means such as one or more skirt portion(s) which are arranged between vertically juxtaposed sub-assemblies in use. The skirt portions substantially prevent or minimize the escape of finer aggregate material from between the stacked sub-assemblies.