The construction industry in Brunei Darussalam has long depended on overseas short-term migrant labour. Major sources of migrant workers include Thailand, Indonesia and Bangladesh. As noted by the Brunei Economic Development Board (n.d.), foreign workers currently make up over one-third of the nation’s workforce. On construction sites, they form a large majority of the total workforce. In retail trade outlets such as small sundry shops, supermarkets and department stores a substantial majority of the staff, especially at lower levels, are from overseas. Migrant workers on construction sites in Brunei Darussalam often do not have full proficiency in the languages used by their supervisors and overseers. Anecdotal evidence from those working in the construction industry, as well as the research conducted in Brunei by Santoso (2009), suggests that workplace multilingualism and the need for effective communication in a lingua franca may have linguistic consequences, such as the development of pidginised or simplified speech forms. There may also be negative economic consequences arising from workplace miscommunication: delays in project completion, and substandard work arising from instructions that are not fully understood. In workplace contexts, where safety considerations are paramount, miscommunication and failure to understand instructions can have serious economic consequences such as budget overruns and delays in project completion. These have deleterious effects on development, on diversification from dependence on oil and gas, and thus on national development. Hence we view this study as aligned to Brunei’s Vision 2035 (Brunei Economic Development Board, n.d.). Similar communication problems may reduce the efficiency and timeliness of house construction, and may affect levels of customer service, cleanliness and sales in department stores and supermarkets. The purpose of this study is to investigate language choice and use among a convenience sample of over 120 migrant workers in a variety of workplaces. Qualitative methods, mainly semi-structured interviews and observations are utilised in order to generate data. The findings show a pattern of language mentoring of newly-arrived workers by those of the same nationality and language that have been in Brunei Darussalam for some time. This enables them to acquire pidginised varieties of Malay and sometimes English which are sufficient for their communicative needs in the workplace. The conclusion raises the issue of whether this needs to be reinforced by instruction in pragmatic competence, so the migrants are not perceived by Bruneians as being impolite.