Human pluripotent stem cells (hPSCs) hold the potential to revolutionize cardiac tissue engineering. Because of their ability to proliferate and differentiate into all cardiomyocyte subtypes they represent an opportunity to regenerate virtually any tissue lost from the over 1 million cardiac disease patients in the United States alone. Studies have shown, however, that hPSCs which are not terminally differentiated pose a variety of risks including teratoma formation and lack of appropriate cell engraftment. It is therefore important to ensure that only well characterized cardiac subtypes are implanted into patients or used for research purposes. Current differentiation protocols generate a mixture of cardiac subtypes, and research on cardiac subtype specification is hampered by the lack of a high throughput method to distinguish cardiac subtypes. This thesis establishes the ability to identify, enrich and characterize cardiac subtypes using MBs. This will provide a robust tool for clinical use of hPSCs in cardiac cell therapy and for analysis of differentiation protocol effects on cardiac subtype formation.