This is an historical review of some of the most important developments in the field of polymer colloids-primarily of those with chemical functionality, with emphasis on their formation, characterization and some applications. The salient researches, which brought about our current understanding of how polymer colloids are formed by homogeneous or heterogeneous nucleation and by subsequent emulsion polymerization, are covered. The early studies of the chemistry and physics of these fascinating systems, especially their surface chemistry, also is dealt with. Included are early work on electron microscopy, light scattering, and neutron scattering by some of the great polymer colloid scientists of this era. The author has taken a rather personal perspective, no doubt slighting many significant historical developments which others may feel are also important. Because this chapter is perforce limited in length, the author apologizes in advance for any omissions.