Mueller Associates, a leading mechanical/electrical engineering firm based in Baltimore, has promoted Robert A. Marino, P.E. to president. Marino previously served as senior vice president and director of operations. He has been with the firm for over 20 years. He succeeds Eugene F. Nerf, Jr., P.E. who has served as both chairman and president of Mueller since 1992. Nerf will continue to serve as chairman of the board.