Modelling endangered languages: The effects of bilingualism and social structure James W. Minett * , William S-Y. Wang Language Engineering Laboratory, Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong Received 22 September 2005; received in revised form 23 March 2007; accepted 3 April 2007 Available online 29 June 2007 Abstract The mathematical model for language competition developed by Abrams and Strogatz allows the evolution of the numbers of monolingual speakers of two competing languages to be estimated. In this paper, we extend the model to examine the role of bilingualism and social structure, neither of which are addressed in the previous model. We consider the impact of two strategies for language maintenance: (1) adjusting the status of the endangered language; and (2) adjusting the availability of monolingual and bilingual educational resources. The model allows us to predict for which scenarios of intervention language maintenance is more likely to be achieved. Qualitative analysis of the model indicates a set of intervention strategies by which the likelihood of successful maintenance is expected to increase. # 2007 Elsevier B.V. All rights reserved. Keywords: Language competition; Language death; Language maintenance; Dynamical system; Agent-based model 1. Introduction The 6000 or so languages spoken on our planet today are the products of numerous millennia of cultural evolution. They encapsulate the experience and knowledge of diverse peoples collected in widely different environments, and are a precious part of the human heritage. With the explosive expansion of a few dominant languages in recent decades, at least half of the world’s languages are critically endangered in that they will soon have no speakers and become extinct (Krauss, 1992; Crystal, 2000). Pagel (1995) estimates that roughly 140,000 languages have ever existed (median estimate), so it is the fate of the majority of languages to become extinct. Fishman (1991) argues that www.elsevier.com/locate/lingua Lingua 118 (2008) 19–45 * Corresponding author. Tel.: +852 3163 4346; fax: +852 2603 5558. E-mail addresses: jminett@ee.cuhk.edu.hk (J.W. Minett), wsywang@ee.cuhk.edu.hk (W.S-Y. Wang). 0024-3841/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.lingua.2007.04.001