The paper, by five authorities who contributed significantly to the second symposium on advances to particle sampling and measurement (October 1979 in Daytona Beach, FL) summarizes salient developments in the field. Current techniques were described as being expensive, complicated, and less accurate than desirable. Significant improvements would result in such benefits as: (1) better understanding and quantification of control device behavior (which could expedite the evolution of more efficient control devices); (2) more accurate assessment of environmental and health effects related to various pollution sources; and (3) use of particulate emission measurements as forms of process monitors. In addition to new developments, there was also considerable interest in inhalable particles (airborne particles with aerodynamic diameters of 15 micrometers or less) since new particulate air-quality standards based on inhalable particles are likely to be established by the EPA. Discussed during the symposium were: impactors (including virtual impactors), aerodynamic particle size analyzers, sample collection and dilution, real-time monitors and data reduction, and prototype instruments.