The late 19th and early 20th centuries were a time when a number of pioneering knowledge organization systems (KOSs) originated. They were also a time when various forms of imperialism influenced social, political, and economic life in the countries where these KOSs were developed. Adopting a case study approach, this paper examines the influence of imperialism on one pioneering KOS of this period – Julius Otto Kaiser’s method of Systematic Indexing (SI). The study describes the institutional milieux in which Kaiser originated SI and gave it its canonical form – the Philadelphia Commercial Museum (PCM) and the Joseph Chamberlain’s Tariff Commission (TC). Evidence is presented to show that both institutions were involved in projects of economic imperialism and that these projects affected their knowledge organization (KO) practices. Then follows an examination of the semantic content and syntactic structure of SI for traces of imperialist influence. Analysis reveals that most traces of imperialist thought in the semantic content of SI occur in its treatment of countries as subjects and that this treatment does not differ significantly from that found in other contemporary KOSs. Evidence is presented that the syntactic structure of complex subject headings in SI was influenced by KO practices at the PCM, which were animated by the economic imperialist assumptions, but that similar structures can be found in another contemporary KOS with no manifest ties to imperialism. It is concluded that the motivations for certain semantic elements of SI reflect by imperialist presuppositions but that its syntactic features are not uniquely or inherently associated with imperialist ideology. Depending upon the analytical perspective that one adopts, then, SI both is and – paradoxically – is not an imperialist KOS.