This paper examines pragmatic variation by gender in market service encounters in Southern Mexico. Following previous research in service encounters (Aston 1988a; Kerbrat-Orecchioni & Traverso 2008; Merritt 1976; Placencia 2008), this study examined 244 food-related transactions (122 male-customers and 122 female customers) that were analyzed according to three levels of analysis: actional (customer-initiated requests), interactional (openings and closings, and request sequences), and stylistic (choice of address forms). The data were examined in light of speech accommodation theory, polite (or expected) behaviour, and pragmalinguistic variation. The study addresses methodological and ethical issues in pragmatics research for the analysis and collection of natural interactional data in commercial settings.