Archaeological monitoring (a rescue excavation of an area 170m long x 13m wide) during the construction of an Anglian Water trunk main between Cressing and Great Horkesley in north Essex recorded an important Roman site at Great Tey. A sequence of Roman trackways and enclosures containing corn-driers represents a crop-processing area dating from the mid-1st to later 4th century. The crop-processing enclosure was enlarged in the mid/late 2nd century, at the same time as the construction of the Great Tey Roman villa 800m to the south-east (NHLE no. 1013516), and would have been part of the villa estate. The initial layout of trackway and enclosure in the mid-1st to early 2nd century was probably related to a farmstead predating the villa. A medieval stock enclosure dating from the 12th/13th to 15th century was recorded beside Brookhouse Road. All features in the excavated area were planned and a sample of most of them was excavated, but investigation was concentrated on several selected areas with a high density of features as these had the greatest potential for producing a coherent and interpretable sequence. These areas were cleaned by mechanical excavator and excavated in detail, but features elsewhere, especially some of the boundary ditches, were investigated only minimally.<1>