In line with what Hull and Stornaiuolo (2010) describe as a cosmopolitan turn in the social sciences and given the growing interest in cosmopolitanism as a result of neoliberalism (Bernstein et al., 2015) and the global rise in the use of English (Seargeant, 2012), this article investigates the ideology of cosmopolitanism by drawing on the constructs of heteroglossia and dialogue (Bakhtin, 1981; Blackledge & Creese, 2013) and Systemic Functional Linguistics (SFL). Using the SFL Engagement framework (Martin & White, 2005) to analyze how cosmopolitanism is constructed in political speeches, official educational documents, and classroom interactions in Singapore, we also examine the ways in which cosmopolitanism is mediated in these discourses and how it impacts the varieties of English that are valued in society and school. Following the analyses of our data, we call for a development of dialogical cosmopolitanism (Canagarajah, 2013), which conceives of cosmopolitanism as a negotiated process and values linguistic hybridity. The article closes with a discussion of the pedagogical implications of the study and highlights that in order to nurture cosmopolitan dispositions among students in language classrooms, some degree of curricular flexibility, tolerance for uncertainty, and deregulation needs to be undertaken.