The history of the use of fire retardants for wooden structures in the US, and the involvement of ASTM Committee D07 in the development of test methods are summarised. By the 1960s, there were three dominant formulations used commercially for pressure-treating wood, and formulations which encapsulated fire retardants had been developed for exterior use. In the early 1980s, second-generation compositions were introduced to eliminate the corrosion and hygroscopic problems associated with the first-generation materials. These comprised either a nitrogen-phosphorous organic compound blended with boric acid, or ammonium polyphosphates with or without additives. The retardants can reduce the strength of timber, particularly in high temperature applications, and ASTM has developed test procedures for the determination of appropriate design reduction factors ( D 5516, D 6305, D 5664 ). 2 refs.