The emerging field of atomization and spray deposition is continually striving to improve the quality of its final products. A major obstacle to achieving consistently high-quality end products is the lack of ability to monitor the various operational parameters associated with spray processes. This paper will present a discussion of the diagnostic techniques that are currently available for monitoring processing parameters, such as droplet size, velocity, and concentration, as well as droplet temperatures and size distributions. To that effect, several methods for obtaining on-line feedback of these parameters are discussed and compared. Techniques such as high-speed cinematography, off-axis holographic cinematography and infrared thermal imaging, are compared and evaluated for their utility in providing information which will elucidate relevant atomization phenomena. In addition, the PCSV-P probe, phase Doppler particle analysis, EPMP monitor, and intelligent sensors are also reviewed and discerned for their usefulness, in making spray atomization and deposition a more controlled process.