The need for particle size control in the manufacture of pharmaceuticals is becoming increasingly apparent as the pharmaceutical industry attempts to capitalize on some APIs with less-than-ideal solubility profiles. Also, significant advances in drug delivery have been made in which a finely divided API, with the concomitant increase in specific surface area, has resulted in increased bioavailability. Precise particle size control technologies have also assisted in the development of drug delivery platforms for the delivery of a medicament to the lung. As these trends have occurred, the need for highly reproducible particle size assessment techniques has grown significantly in the past decade. The interest in particle size measurements will remain high, particularly in view of FDA trends toward recommending more thorough descriptions of particle size distributions in submissions in which the emphasis of a drug product claim is based in a tightly controlled particle size.