Development of effective drug delivery systems is important for medicine and healthcare. Polymer particulates (micro- and nanoparticles) have opened new opportunities in the field of drug delivery by overcoming various limitations of conventional delivery methods. The properties of polymeric particles can be readily tuned by precisely engineering the constituent blocks of polymers for improving drug loading, release rate, pharmacokinetics, targeting, etc. The end-groups of various polymers can be readily modified with ligands making them suitable for recognizing by cell-specific receptors, providing cellular specificity, and superior intracellular delivery. This review will mainly cover delivery of many potential drugs and biomolecules by means of polymeric microparticles, nanoparticles and copolymer micelles or assemblies. An overview about formulation methods of polymer particulates has also been addressed. Attempt has been made to cover all the potential polymers that are well known in pharmaceutical history.