Sampling and analysis requirements for the characterization of ambient particles are reviewed. The choice of sampling equipment and characterization procedures for ambient particles are often dictated by the objectives of the experiment. The paper describes the procedures and the application of the following instrumental methods for the characterization of aerosols: x-ray fluorescence (XRF), neutron activation (NAA), ion exchange chromatography (IC), x-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM). A procedure for the application of gas phase denuders to measure nitric acid and nitrates and a combustion procedure to measure the carbon content of particles are also described.