Polymer/clay nanocomposite particles are particles with at least one component being structured on the nanoscale, and are anticipated to be used in coatings, adhesives, and films for barrier properties. In this chapter we will focus on three areas of research leading to polymer/clay nanocomposite particles: use of nascent clay as the stabilizing agent in direct emulsion polymerization, use of hydrophobized clay as the stabilizing agent in inverse emulsion polymerization, and encapsulation of exfoliated clay platelets via emulsion polymerization.