Development of increasingly complex cellular systems will be a major challenge for the next decade and beyond, as we use the knowledge gained from the sub-disciplines of tissue engineering, synthetic biology, micro-fabrication and nanotechnology, systems biology, and developmental biology. This session describes the current state-of-the-art in differentiating source cells from more primitive, pluripotent cells; organizing cells into populations of a single cell type to produce the components or building blocks of higher order systems; and combining multiple cell types to produce greater functionality. As these “biological machines” increase in capabilities, exhibit emergent behavior, and potentially reveal the ability for self-assembly, self-repair, and even self-replication, questions arise regarding the ethical implications of this work. Future prospects as well as ways of addressing complex ethical questions will be addressed.