I'd like to elaborate a little bit on the answers that have already been posted on this issue. The way I view it, post and beam is a structural system, while timber frame is a construction method. Any time distance is spanned by a horizontal member transferring its load to vertical members, it is post and beam. Timber frames are post and beam, as are modern timber homes with steel connectors. The Parthenon and other structures from classical Greece are post and beam. Modern steel skeleton skyscrapers are post and beam. Pole barns are post and beam. And stick-built houses are post and beam, as has been said, with the posts and beams reduced to minimal size. I would even maintain that geodesic domes are post and beam, although the demarcation between what is a post and what is a beam is somewhat blurred, since the whold structure forms a complex three-dimensional truss. Examples of construction that are not post and beam include log building, in which loads are transferred directly from one horizontal member to another until they reach the foundation; structural masonry, where horizontal lintels carry loads to solid walls on either side of the opening; and arches, both round as in the aquaducts of ancient Rome or the barrel vaults of the Washington DC subway system, and corbelled as in the temples of precolumbian mesoamarican civilizations. Anyone care to comment or elaborate?