Spread of Flame is one of a series of tests being developed by ISO/TC 92 - Fire tests on building materials and structures. Other tests in this series are for example ignitability, rate of heat release and smoke production. The members of ISO/TC 92/WG 4 have decided to carry out an interlaboratory test program, "Round Robin" on the ISO - Spread of Flame test. Ten different materials have been circulated to a number of laboratories. The test was carried out according to the Draft Technical Report 5658/1. The principles of the test are given in Annex B as: "This test method examines the ability of a surface, when exposed to radiant heat, to produce a horizontal flame spread on a vertical surface after ignition with a small ignition source." Draft instructions for WG 4 Round Robin tests with ISO Spread of Flame apparatus, Vandervelde - ISO/TC 92/WG 4 N 380, has been used in conjunction with DTR 5658. This report presents the data from Statens Provningsanstalt, Division of Fire Technology, Borås, Sweden.