The solid dispersion has become an established solubilization technology for poorly water soluble drugs. Since a solid dispersion is basically a drug-polymer two-component system, the drug-polymer interaction is the determining factor in its design and performance. In this review, we summarize our current understanding of solid dispersions both in the solid state and in dissolution, emphasizing the fundamental aspects of this important technology. (C) 2014 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.V.