A typological investigation of errors in the use of English in the bilingual and multilingual linguistic landscape of Tehran Ahmadreza Mohebbi a and A. H. Firoozkohi b a Department of Foreign languages, Kharazmi University of Tehran, Tehran, Iran; b Department of English language and literature, Shahid Beheshti University, Tehran, Iran ABSTRACT The present paper examined the errors occurring in the use of English in the linguistic landscape of Tehran, the capital of Iran. To this end, a total of 400 bilingual (Persian and English) and multilingual signs (Persian, English and Arabic) were culled from the landscape of the city in a course of eighteen months. Having analysed all the signs, 101 errors in terms of translation and word choice, spelling, transliteration, grammar, and L 1 influence were detected. Adopting a mixed methods approach, the findings of our study revealed that errors on top-down signs significantly exceeded those of bottom-up. The results also showed that spelling errors and mistranslations vastly outnumbered other types on both top-down and bottom-up signs. Being the first paper in error typology in the use of English in the LL in the context of Iran, the study concludes by reviewing how language policy and foreign language education could result in inaccurate use of English in the LL. In the end, suggestions for further studies have been propounded in other areas of LL for those who are interested in this fascinating line of research. ARTICLE HISTORY Received 6 November 2018 Accepted 11 February 2019 KEYWORDS Linguistic landscape; error typology; bilingualism; multilingualism; top-down signs; bottom-up signs Introduction Although the modern multilingual era has witnessed an exponential growth in the use of written mode of language as presented on billboards, window cases, commercial ads, official notifications, and street signs in different languages, both common people and decision makers tend to take its significance for granted. Trivial as it may seem, yet, this issue came to catch the attention of Landry and Bourhis (1997) who coined the term lin- guistic landscape (referred to as LL from now on) by offering the first definition as ‘the language of public road signs, advertising billboards, street names, place names, commer- cial shop signs, and public signs on government buildings combines to form the linguistic landscape of a given territory, region, or urban agglomeration’ (p. 25). Language and land- scape are obliged to each other. Nash (2015) stated that ‘language demands landscape, landscape expects language. Spatiality is at the centre of a mobile nexus of interaction between language and landscape and language in landscape’ (p. 380). A major impetus for studying linguistic/semiotic landscape is provided by Scollon and Scollon (2003), a study on geosemiotics, investigating the social meaning of material location of signs in © 2019 Informa UK Limited, trading as Taylor & Francis Group CONTACT Ahmadreza Mohebbi ahmadreza_mohebbi@outlook.com This article has been republished with minor changes. These changes do not impact the academic content of the article. INTERNATIONAL JOURNAL OF MULTILINGUALISM https://doi.org/10.1080/14790718.2019.1582657