More than 1200 individual smoldering combustion tests were conducted on fabrics used as upholstered furniture covering, in combination with different substrates. Significant differences in smoldering characteristics of Class C and D upholstery fabrics were evident when used over typical furniture substrate materials. The nature of the substrate or substrate system used with upholstery fabrics may significantly influence the smoldering properties of fabric/substrate composites. The results of cigarette tests of upholstery fabrics over fiberglass board and non-FR cotton batting may not reflect the actual smoldering properties of fabrics when used over actual furniture constructions.