Fine particulate matter (PM2.5) causes the most health damage among non-biological air pollutants inhaled in homes. Enhanced filtration and other particle removal systems can meaningfully reduce fine particle concentrations and exposures in residences. Enhanced filtration technologies incorporated in various system designs are being installed in both new and existing U.S. residential buildings, and in some cases creating substantial new energy loads despite inconsistent effectiveness in reducing exposures. Research is needed to support guidance on effective technologies, system designs and controls. A key element of this research effort is the ability to quantify performance of filtration systems as installed in homes. This guide provides background information on the factors that impact filtration system performance and specific guidance on how to implement installed performance evaluations. The guide is intended to inform building scientists, healthy homes researchers, and practitioners interested in conducting an evaluation or understanding an evaluation performed by others.