The paper discusses issues related to sampling and analysis that should be addressed in the design and performance of source characterization testing, whether performed in small chambers, large chambers, test houses or in the field. Selection of the sampling method (e.g., whole air samples, on-line sampling, or sorbent media) and design of the sampling protocol, for example, are important factors that are a function of volatile organic compounds (VOCs) in the emissions and the emissions profile. The applicability of different sorbent media or whole air methods depends on collection efficiency, recovery efficiency, and storage stability. Changing VOC concentrations and the often large differences in concentration between individual compounds may make sampling difficult. Several factors (e.g., water vapor concentration) affect the selection of thermal desorbers (for sorbents), the concentration method, gas chromatography columns, and detectors. The paper also highlights quality assurance issues and reporting of measurement methods and results.