The engagement of Sierra Costello of Chambersburg to Steven Bilous has been announced by her parents.

The bride-to-be is the daughter of Mr. and Mrs. Dimps Hawthorne of Dillsburg, Pa., and Mr. and Mrs. Steve Costello of Robesonia, Pa. Her mother, Mrs. Hawthorne, is the former Val Bowman, a graduate of Lehighton High School. The bride-to-be is also the granddaughter of the late Victor and Madelyn Bowman of Lehighton and the late Esteben and Marina Costello of Palmerton.She is a 2008 graduate of Kutztown University and is employed by the state with the Department of Public Welfare.The prospective bridegroom is the son of Mr. and Mrs. Robert Bilous of Camp Hill, Pa. He is a 2008 graduate of Lycoming College, and is also employed by the state with the Department of Public Welfare.A fall 2010 wedding is planned.