This paper presents an extensive review of the research literature on Colloquial Russian (CR) in the past 50 years with an extra focus on the teaching of Russian as a foreign language (RFL). First, using Zemskaja’s understanding of russkaja razgovornaja reč’ (1973, 1979, 1987, 2011, 2016), the article offers an overview of CR’s linguistic features and, second, it looks at the recommendations issued in the literature as to whether and when colloquial peculiarities should be taught—be it for receptive or productive communicative competence. Third, the paper presents the results of an empirical study, which was conducted to show how linguists, Russian instructors and teachers in German-speaking countries treat CR in their lectures and seminars on Russian linguistics as well as in secondary RFL classes and where their preferences lie. Based on the findings from this survey, the article then addresses what researchers preach and what practitioners teach and makes suggestions on how to narrow the gap between theory and practice, claim and reality.