The engagement of Sara L. Nelson of Cheektowaga and Casey M. Essary, also of Cheektowaga, is announced. A July 9 wedding in First Presbyterian Church of Monroe, Mich., and a reception in LaRoy's, Monroe, are being planned. The future bride, daughter of Joanne Szelgia of Lockport and David Nelson of Bowling Green, Ky., is an employee of Nanodynamics. Her fiance, son of Frederick and Karen Essary of Monroe, is employed by General Motors Powertrain. The engaged couple are graduates of Kettering University, Flint, Mich.