This paper examines the relationship between linguistic plurality and the rationale of advertising decisions. The presence of two or more languages on one market modifies the traditional advertising problem, and in the absence of literature on the subject, a logical first step is to develop a basic model. This paper presents a simple model of sales to different language groups as a function of the level of advertising in each language, language attitudes, incomes, and an advertising response function. It generates a set of hypotheses about the necessary and sufficient conditions for bilingual advertising to become more profitable than advertising in the majority language alone. A few of the model's results are presented in the paper, showing why indifference to language in the public will produce a unilingual commercial environment, or by how much consumers' resistance to dominant language hegemony can increase the range over which bilingual advertising is profitable. This generates policy recommendations about the level of respective group incomes, the efficiency conditions of boycott or goodwill campaigns, and the role of product differentiation and market structure. This model is intended as a benchmark, and several extensions are suggested, in order to adapt the model to specific cases or allow for the inclusion of more complex causal links. In its present form, it shows how integrating information on the existing commercial environment can provide instruments for language planners.