This chapter discusses the analysis of particles as captured from fluid streams by analytical methods which use electrons. Each of the analytical techniques is, in itself, complex and requires extensive description and explanation of numerous factors related to both the instrumental technique itself and specimen preparation required of particulate matter for that technique. All of the techniques are meant to be related to particles captured from fluids. They might well also apply to particles found imbedded in solids. There are a number of steps involved in obtaining information from any particulate matter which in general, include the following: collection, sample selection, sample preparation, electron microscopy or spectroscopy, and interpretation of results. The observational techniques are given in terms of their capabilities. Without automated techniques of sample analysis, any investigation will sample very few particles because of the labor involved in making each analysis. This is particularly true of quantitative analysis.