This article describes how to prevent abutment failures in unreinforced structural brick masonry arches. It is based on a recent investigation of over 70 arches in Washington D.C., Massachusetts, Pennsylvania, and Virginia conducted by a professor and graduate student from Penn State and a staff engineer from the Brick Institute of America. The researchers classified the failures into three categories: (1)abutment displacement due to moisture and thermal expansion of the masonry; (2)insufficient abutment stiffness; and (3)foundation settlements of abutments. At least one of these failures was noticed for each of the most common arches used in residential and commercial building construction--jack arches, segmental arches, and semicircular arches. In older masonry buildings (over 100 years), the most common mechanism of arch failure was slippage of voussoirs or whole sections of the arch ring. Loading conditions, form of building construction, and age of the building, or combinations of these factors, were directly responsible for the failures observed, most of which are failures that affect the serviceability of the masonry wall (rather than total arch collapse). Serviceability is the ability of the arch to support the imposed loads safely to assure its proper performance during in-place use. Arch loading conditions can be described as uniform or concentrated. Uniform loads derive from the triangular area of masonry above the arch opening. Concentrated loads occur when beams, girders, or trusses framing into the wall above the arch exert pressure on the arch. Arch design is influenced by: whether the the wall is triangular or square; whether it has many projected or recessed areas; or whether the wall is flat or curved.