Intricately manufactured, visually stunning, and coveted across vast geographic distances for generations, Columbia River-style mountain sheep horn bowls and ladles exemplify the quintessential art form of the Chinookan peoples of the lower Columbia. While these objects are prized as heirlooms and sought as iconic additions to Native art collections, this thesis provides first systematic art historical study dedicated solely to these highly valued sculptural vessels. Based on research in twelve museum collections, this paper analyzes a sample of ninety-eight objects acquired by these institutions between 1850 and 1921 CE and their ethno-historical context, stylistic details, and functional evolutions. Ultimately, this thesis proves the origin of these vessels in a Wasco/Wishram village near the Dalles, their importance in understanding the Chinookan art style, and their sustained cultural value over time in both Indigenous and Euro-American spheres of exchange.