This paper summarizes the sixteen technical papers and nine posters presented in the above session at the Particle Technology Forum Meeting in Denver. Abstracts of all papers and posters are provided, along with a perspective on the changing face of particle characterization in the 90’s. Comparing this session to those of a decade ago, movement from laboratory to process measurement is strongly indicated. This requires a new type of instrument that is robust and fast, but with the ability to operate in high concentration and often hostile environments. Interpretation of data from complex and often non-user friendly process measurement signals places more demands on process operators. Particle size distribution remains the primary parameter of interest with concentration and morphology of concern, but to a lesser degree.