The increasing diversity of learners and teachers of languages (of both English as an Additional Language or Dialect [EAL/D] and Languages) coincides with major efforts to reconceptualise the nature of additional language learning towards multilingual and intercultural orientations. In this paper I first describe the policy context of EAL/D in Australia, which shapes the reality of EAL/D provision and practices. I then discuss some expansions of key constructs related to additional language learning and the way in which these might inform EAL/D practices. In particular, I focus on the need to consider (a) the mediating role of languages and cultures in language learning, and (b) the need for an interpretive, reflective and reflexive stance towards learning, highlighting how these notions pertain to both student and teacher learning. Next, I discuss examples of teachers' work with students drawn from two case studies of EAL/D practice that explore these notions in a programme of ongoing practitioner research. I conclude by discussing the situatedness of teachers (and their students), the need to consider the personal interpretations of meanings that teachers make and that form their professional learning, and the need for a kind of reflexivity that will lead to the ongoing development of self-awareness as a basis for working in and with diversity.