The aim of the article is to reflect the types of influence of German as a contact language on the Latvian language of science in the interwar period from 1918 to 1940. During this period, the Latvian language acquired the status of the official language. However, the language of special use, including the language of science, was still developing. This is evidenced by the variability in the vocabulary of special use, which often occurred under the influence of contact languages, mainly Russian and German. The article discusses the existing research on the influence of the German language on the Latvian language of science, as well as analyses the scientific and popular scientific articles of the humanities and social sciences published in Latvian from the “Gazette of the Ministry of Education” (Izglītības Ministrijas Mēnešraksts) (1920–1939), and natural and engineering science articles from the “Articles of the University of Latvia” (Latvijas Universitātes Raksti) (1921–1943). The study uses content analysis, as well as qualitative and quantitative analysis. The influence of German as a contact language is manifested in the use of special Latvian vocabulary with the indicated equivalents in German. The articles and lectures in humanities and social sciences are translated from German into Latvian and published. In the field of natural and engineering sciences, the collection can even establish bilingualism, as abstracts in Latvian are attached to articles in German, and vice versa – articles in Latvian are published with summaries in German, as well as academic lectures are published in parallel in both German and Latvian. The literature used in scientific articles is based on secondary sources in German. In the humanitarian and social spheres, thematic review articles are written using sources in German. Consequently, it can be concluded that the German language was an important “lingua franca” for the Latvian language of science during the interwar period (1918–1940). Further research should be related both to the study of the impact of Russian as a contact language on the Latvian language of science and the study of the factors of multilingualism in the Latvian science of this period.