The properties of a new series of ductile beryllium-aluminum alloys, which were specifically designed for use in aerospace vehicles, are described. Young's modulus, bend, and tensile properties of sheet and extrusion alloys containing between 24 and 43 per cent aluminum are presented. The elevated-temperature tensile properties to 1000 F (540 C) are given for both rolled and extruded material containing 36 per cent aluminum. The effect of temperature on Young's modulus of an extruded Be-31.4 per cent Al alloy is also given to 1000 F (540 C). Structural efficiency comparisons are made between beryllium and competitive materials, in some cases, to 1000 F (540 C). The improved ductility, machinability, weldability, and formability of these new alloys, as well as the lack of brittleness and freedom from chemical etching requirements, as compared to currently available commercial purity beryllium, should result in significantly lower installed cost than for beryllium. Substitution of beryllium-aluminum alloys for currently used HM21A-T8 and HK31A-H24 magnesium alloys could result in weight savings on the order of 40 per cent.