Living systems interact with their environment in a tremendous diversity of ways. Mechanical signals are now recognized as a major mechanism of communication, which can influence cell migration, growth, and differentiation. The vision of the Center for the Mechanics and Engineering of Cellular Systems is that a comprehensive understanding of the input and output of mechanical signals inside living cells, and between cells and the environment is essential in numerous areas. Significant improvements in the prevention and treatment of cancer, birth defects, and aging, as well as novel applications such as engineered tissues, nutrition and biological nanomachines, may be achieved by manipulating mechanical interactions in integrated biological systems at the molecular, cellular, and multi-cellular scales. Through leveraging the long-standing transdisciplinary culture of Carnegie Mellon University, the Center is built upon strengths in engineering, physics, life sciences, and computation across multiple departments and colleges.