This study explores English-dominant speakers' and English learners' knowledge of (in)formal stylistic variants, their choice of (in)formal styles in relation to social context, their preferences in the use of select (in)formal stylistic variants, and their beliefs about the influence of their other languages. Ten English-dominant undergraduates in Canada, 10 international English-as-a-second-language undergraduates in Canada, and 11 English-as-a-foreign-language undergraduates in Slovakia completed a questionnaire and composed 6 short e-mail messages, each embedded in a unique social context defined by the intended reader (ranging from completely unfamiliar to extremely familiar) and the communication purpose (ranging from completely transactional to completely interactional). Differences were found among the groups in their knowledge of (in)formal stylistic variants, their choice of style, their use of some (in)formal variants, and reported effects of their other languages. This study concludes that primarily classroom-instructed English learners who wish to learn how English-dominant speakers approach expression of formality would benefit from explicit instruction. It further concludes that more research is necessary to identify factors driving individual knowledge of (in)formal variants and preferences in their use, particularly in relation to overall communicative competence and the context of language acquisition and use.