Kevin and Sue Frankenbach of 6207 County Road 258, Hannibal, Mo., have announced the engagement of their son, Adam Carlton Frankenbach of Palmyra, Mo., to Rebecca Ann Grisham of Jefferson City, Mo. She is a daughter of Kenneth and Cecilia Rademan of Koeltztown, Mo.

The bride-elect is a 1994 graduate of Fatima High School and a 1998 summa cum laude graduate of St. Louis University with a degree in communications. Miss Grisham is director of communications with the Missouri Corn Merchandising Council.

The prospective bridegroom is a 1999 graduate of the University of Missouri-Columbia, where he was a member of Beta Sigma Psi. Mr. Frankenbach is an area sales manager for Agri-King.

The couple will be married Sept. 20 in Immanuel Lutheran Church in West Ely, Mo.