Biopolymers have a myriad of applications which may be considered as novel not only in agriculture and agribusiness, consumer science, sports, transparent and optical materials and in biological and medical materials but also in controlled drug delivery and targeting. This chapter will highlight the major applications of biopolymers as enunciated in the preceding sentence with special emphasis on the use of engineered polymers and polymeric systems in controlled drug delivery and targeting. Successful pharmacotherapy intervention requires strict control over the spatial and temporal characteristics of drug delivery. Engineered polymers are the materials used today to construct carriers with controlled drug delivery properties, that is, carriers which could perform one or more of the following: (a) increase drug availability to the target cells, (b) increase selectivity towards the target cells, (c) release their drug load only at the site of drug action (or nearby) in response to internal or external stimuli (e.g. pH or temperature changes) and (d) release drug only when it is required in response to biological signals (e.g. an increase in glucose levels in blood). The development of such polymers has caused advances in polymer chemistry, which, in turn, has resulted in smart polymers that can respond to changes in environmental conditions. The responses vary widely from swelling/deswelling to degradation. Drug-polymer conjugates and drug-containing nano/micro-particles have been used for drug targeting. Engineered polymers and polymeric systems have been used in new areas, such as molecular imaging as well as in more recent applications in nanotechnology.