Major routes to polymer property tailoring during processing, and the significant interactions between processing and product properties are discussed from the viewpoint of some of the research being undertaken iri our IRC laboratories. Reactive injection processing of polymers, polymer alloys and polymer composites, and reactive extrusion modification of polymers illustrate processing which involves molecular organisation in the polymer chain to achieve desired product properties, and also larger scale organisation of the polymer. Solid phase processing techniques demonstrate organisation of already formed polymer chains. Orientation techniques and hot compaction of high modulus polymers show the potential for enhancing the properties of certain polymers, through controlled processing. Adding reinforcement forms part of the same strategy as solid phase deformation, namely adding value to (or compensating for) existing polymer properties, and novel thermoplastic composites, including biomaterials, are discussed in this context. Techniques involving manipulation of polarity in the polymer chain, for potential use of the materials in ’devices’ are presented briefly. Finally, the significance of process control for melt processing of polymers is discussed.