This report provides guidance on 'ignitability' tests for building products. It describes the principles of ignitability and characterizes different ignition sources. Results of small-scale ignitability tests may be used as a component of a total hazard analysis of a defined fire scenario. It is therefore, important that the flame or radiative source chosen is fully characterized so that relevant conclusions may be made from the test results. Guidance given in this report may also have relevance to other application areas (e.g. building contents, plastics, etc)