Polymeric biomaterials are routinely used to fabricate micro- and nanoscale carriers for drug delivery. Encapsulation of drugs in polymeric carriers protects them from enzymatic degradation and provides sustained release over prolonged periods. Further, encapsulation also allows drug targeting via cell and tissue-specific ligands. The performance characteristics of polymeric carriers in the body, for example circulation times, macrophage clearance, targeting and drug release rates, depend on several particle parameters including size, shape, surface chemistry and mechanical strength. Developing quantitative relationships between carrier design features and biological performance is crucial for fabricating next generation drug delivery carriers. I will overview some of the important design features and their role in drug delivery. I will particularly focus on engineering particle shape, a design parameter that has received little attention in the past. I will discuss methods to fabricate particles of several distinct shapes and their impact on key processes in drug delivery, in particular phagocytosis, the clearance of particles by macrophages. These studies reveal that particle shape provides a new dimension in engineering of polymeric carriers and opens up new opportunities in drug delivery.