Messaging tools such as SMS are effective tools for foreign language learning. While many quasi-experimental studies confirm efficacy and positive student attitudes towards these types of tools, little is known about existing teaching practices that utilize messaging tools in tertiary contexts, or the attitudes of students or instructors towards them. This qualitative study investigates the use of WhatsApp, one popular messaging application, in teaching English as a Foreign Language (EFL) through examining the attitudes of Preparatory Year students and faculty members at a university in the central-north of Saudi Arabia. Thematic analysis of focus group interviews indicated that WhatsApp is used in EFL instruction for information exchange, language learning support, and language practice. This is achieved through teacher-directed learning, peer learning, and autonomous learning instructional strategies. Thematic analysis also identified the affordances and affective outcomes of using WhatsApp. Student and faculty attitudes towards WhatsApp were positive although some faculty members expressed reservations towards its use. It is argued that applications such as WhatsApp should be leveraged to encourage autonomous and peer learning, repositioning instructors as facilitators, and to develop learning communities. However, increasing the informal, anywhere-anytime learning supported by mobile learning must be tempered with guidelines for students regarding faculty contact hours and response times to allay faculty fears and encourage greater student autonomy.