In order to discuss evidence collection at an arson scene, we first must explain the intricacies of arson investigation. In this chapter we identify several aspects of arson investigation, including what an arson investigator can and cannot do, long-standing myths about burn patterns, what is a competent ignition source, hurdles that have to be overcome in arson cases, what tools are available to the arson investigator and what types of evidence should be collected by the arson investigator.