A non-aqueous liquid heavy duty laundry detergent composition comprising a suspension of builder salt in liquid nonionic surfactant in which the stability of the composition is improved by the addition of small amounts of organophilic modified clay. Stability is further enhanced by grinding the solid particulate matter, including builder salt, bleach and other minor ingredients to a particle size below about 15 microns. The preferred organophilic modified clay is a water-swellable smectite clay in which the metal cations are totally or partially exchanged with a mono- or di-long chain quaternary ammonium compound.