Melissa Greer and Matthew Dreyfus were married Oct. 18 at Grey Rock Mansion in Baltimore, with a reception following. She is a biologist for the Environmental Protection Agency in Crystal City, Va., and is the daughter of James and M.J. Greer of New Hartford. The bridegroom is a chemist for the Consumer Product Safety Commission in Gaithersburg, Md., and is the son of Barbara and Ronald Dreyfus of East Setauket. The bride earned a master of public health degree from The George Washington University. The groom earned a PhD in analytical chemistry from the University of Delaware. They live in Arlington, Va.