Charlie is recognized internationally for his research on photosynthetic electron transfer and energy conversion. His group has contributed to a clearer understanding of ATP synthesis energized by both non-cyclic and cyclic electron transfer in chloroplasts, reactions catalyzed by both photosystems 1 and 2 and the chloroplast ATP synthase. The greatest part of his research efforts have been directed at understanding photosystem 2 and its associated water oxidation reaction. At an early stage in his career, Charlie devised a method for isolation of this redox enzyme, now known as the “BBY” preparation, in a highly active form and has characterized the roles played by the extrinsic proteins associated with the photosystem. In the course of this research, his group discovered that calcium is an essential cofactor of the oxygen evolving reaction, and other research has scrutinized the role of chloride, which is also an essential cofactor. Using the tools of molecular biology, Charlie has been able to reconstitute polypeptide-depleted photosystem 2 with site direct mutants that have revealed structural and functional properties of PsbO, the extrinsic protein that is a universal constituent of the oxygen evolving reaction in all organisms examined to date. His research has involved a number of productive collaborations with both biophysicists and plant molecular biologists. Charlie spent his entire career at the University of Michigan, where he now holds the title of Alfred S. Sussman Distinguished University Professor Emeritus. He has been the recipient of Guggenheim and Fulbright fellowships, and served on a number of advisory panels at federal funding agencies. Charlie received his post-doctoral training with Efraim Racker at Cornell, after obtaining his Ph.D. in biochemistry at Indiana University with Anthony San Pietro. His undergraduate degree, also in biochemistry, is from Iowa State University.