Late Classic interaction between Copan and western El Salvador has been archaeologically recognized in prestige items, monumental influences, and the common use of Copador ceramics. An inscribed flask excavated in 1952 in the main pyramid at Tazumal, El Salvador provides historical evidence for these ties. The flask is dedicated as the property of K'ahk' Uti' Witz' K'awiil (Copan Ruler 12), a long-lived seventh-century ruler who presided over the expansion of Copan's influence far outside of the Copan valley. The flask is the only hieroglyphic text from El Salvador naming a recognizable individual or that can be dated to an absolute calendrical span, one of only a few miniature Classic Maya vessels tagged with an individual's name, and the only one naming an ajaw (lord). The vessel's text, iconography, and context brings the political relationship between Copan and western El Salvador into sharper focus.