The Society of Antiquaries’ excavation of Silchester’s Insula IX in 1893-4 left most of the stratigraphy undisturbed. A new programme of work has shown that the Insula underwent radical change, c. AD 250/300, with the construction of new workshop and residential buildings on the orientation of the Roman street-grid, following the demolition of mid-Roman buildings arranged on different, pre- and early Roman alignments. The plans of several properties and individual buildings were recovered, and analysis of the rich range of artefactual and biological data has allowed a detailed and differentiated characterisation of the life and occupations of the inhabitants in the 4th century. The context of the 5th century ogham-inscibed stone is explored and the history of the insula is followed into the 5th/6th century.