||Treatment and management of heart disease is challenging due to the heart's limited ability to self-repair. Although current approaches to manage heart disease, such as pharmacotherapy, medical devices, lifestyle changes, and heart transplantation, have improved and extended the quality of life for millions of individuals, they have inherent shortcomings. Future strategies to manage heart disease will likely be based upon a combination of biological and engineering approaches through cell therapy and tissue engineering strategies, both of which have the potential to regenerate the myocardium and improve cardiac function. However, a key hurdle in applying biological approaches is our limited ability to produce reliable tissue to study disease progression and tissue development, therapeutic intervention, drug discovery, or tissue replacement. Establishing hallmarks of the native myocardium in engineered cardiac tissue is a central goal and appears to be required for creating functional tissue that can serve as a surrogate for in vitro testing or the eventual replacement of diseased or injured myocardium. The objective of this research was to apply an engineering approach to develop tools and methods to produce engineered cardiac tissue and characterize both native and engineered cardiac tissue. Three phases of research included: 1) the development and utilization of a framework to characterize microstructure in living cardiac tissue using confocal microscopy and local dye delivery, 2) the development a next-generation bioreactor capable of continuously monitoring force-displacement in engineered tissue, and 3) the application of confocal imaging and image analysis to quantitatively describe features of the native myocardium, focusing on myocyte geometry and spatial distribution of a major gap junction protein connexin-43, in both engineered tissue and native tissue.