The areas of macromolecular assemblies in polymeric systems are reviewed and the applications for useful products or processes are discussed. The challenges in macromolecular assemblies in polymeric systems are to design and synthesize new molecules which can assemble into macromolecular structures which have useful material properties. There is a need to be able to predict the collective properties of the assembly from a knowledge of the properties of the individual molecules.Unconventional materials such as polymers containing moieties which have optically active, magnetic, catalytic or other properties may find a variety of new applications in microelectronics, laser technology, magnetics, communications, electro-optics, bioengineering and biotechnology, catalysis and membrane separations. For example, the computer technology in the early part of the coming century will be a hybrid of microelectronics and integrated optics. Increased performance will require fabrication of macromolecular assemblies based on inexpensive materials processed at low temperatures with high yield over large areas. For optical applications, it is known that organic materials for ultrathin films have superior physical properties compared with those of inorganic materials. Organic materials have a higher damage threshold to laser irradiation than inorganic materials. Organic materials in the form of polymers offer superior mechanical properties, higher damage thresholds and improved stability compared with properties offered by low molecular weight materials. Ultrathin polymer film systems may form the basis of new logic, memory, and display elements if they can be fabricated in highly ordered form so that their structural, surface and interfacial properties can be understood and exploited.