Abstract A long-term laboratory study has investigated how cement-type, aggregate-type and curing, affect the susceptibility of concrete to the thaumasite form of sulfate attack (TSA). The cements were Portland cement (PC), sulfate-resisting Portland cement (SRPC) and a combination of 70% ground granulated blastfurnace slag (ggbs) with 30% PC. These were combined with various carbonate aggregates or a non-carbonate control. Initial curing was either in water or in air. Concrete cubes were immersed in four strengths of sulfate solution at 5 and 20 °C. This paper reports the results after up to six years of immersion in sulfate solution. Deterioration, consistent with TSA, was observed on many of the PC and SRPC concretes that had been made with carbonate aggregate and stored in sulfate solutions at 5 °C, with SRPC providing no better resistance to TSA than PC. Good quality concretes made with 70%ggbs/30%PC showed high resistance to TSA and the presence of carbonate in the mix substantially improved their general sulfate resistance. An initial air-cure, proved beneficial against both the conventional and thaumasite form of sulfate attack.