Smart materials have the ability to respond to changes in their environment by variations in their molecular structure or in their physicochemical properties. Shape-memory and shape-changing polymers are examples for this class of materials, whose capability to perform stimuli-induced active movements has inspired engineers to develop heat-shrinkable packing materials, smart textiles or morphing structures for aerospace vehicles. In the last 15 years these materials have created significant interest in the field of biomedicine, e.g. in minimally invasive surgery for the insertion of self-inflating bulky medical devices. The progress in material chemistry, physicochemical characterization techniques, assessment of biomaterial interaction with cells and tissues, and computer-assisted modelling motivates the exploration of knowledge-based approaches for the design of active polymer systems. However, these active polymers are not restricted to actively moving materials. They can offer a wide-spread spectrum of functions, including controlled release, swellability, and degradability, that may be controlled by suitable stimuli. The concepts for the design of smart polymers with the associated processes can be categorized by the targeted device (e.g. coating, particles) and the nature of the function. Beside shape-memory polymers material systems of interest are stimuli-sensitive hydrogels and nanocarriers for the targeted administration of drugs or genes.