The process of complexation, whereby two polymers interact to form a complex, has been studied with reference to poly(N-isopropylacrylamide-co-methacrylic acid) and poly(N-vinylpyrrolidone). The degree of linkage, theta, and diameter of particles in water have been determined as a function of temperature and molar ratio of participating polymers. It was found that theta and the mean diameter are dependent on the emperature and concentration of poly(N-vinylpyrrolidone).