The Piper House at Antietam National Battlefield in Sharpsburg, Maryland, is an important cultural resource in the battlefield landscape. Built in the second quarter of the nineteenth century, the house has undergone five phases of construction. The Piper Farm was in the center of the Battle of Antietam on September 17, 1862, but is also a good representative example of a vernacular farmhouse in Washington County, Maryland. This report assesses the significance of the house and farm outbuildings as a contributing resource to Antietam National Battlefield's National Register of Historic Places designation, investigates the building chronology and historic construction methods, and provides recommendations for the preservation of historic fabric. This analysis describes the integrity of historic fabric and character defining features.