Vernacular architecture constitutes over ninety per cent of the worlds built structures. When compiling the first encyclopaedia of the worlds vernacular buildings, Paul Oliver confronted fundamental problems of definiton and classification: by whom? of what culture? for what purpose? Solutions to the problems raised by these basic prepositions are conditioned by the pre-positions taken, whether they are indigenous or disciplinary. Oliver discusses whether cultures and their architectures are comparable and the extent to which cultural bias pre-conditions perceptions of vernacular traditions. Paul Oliver taught arts and history at the AA from 1961-73 and was the first head of the AA Graduate School. He was Associate Head of the School of Architecture at Oxford Brookes University where he has been carrying out full-time research in vernacular architecture since retiring in 1988. He is the author of several books on blues and African American music.NB: Audience questions inaudible during Q & A.