Abstract 4D printing is an emerging technology that enables printing of smart constructs that can transform (e.g., reshape or self-assemble) over time to perform programmed functions. Using a variety of 3D printing techniques, through computer-controlled, layer-by-layer deposition of materials in successive layers, 4D printing creates programmable objects that can respond to external/internal stimuli (e.g., temperature, humidity, etc.) without relying on sensors or chips. In this chapter, we introduce a variety of 4D printing strategies, utilizing different smart materials including temperature-sensitive, electrically-sensitive, and cell-traction force-sensitive materials. We will also explore some of the current applications of 4D printing in creating actuating cardiac tissues.