This paper reports on a teaching experiment in an Australian adult numeracy class that used audio and video tapes to record the talk of students as they participated in a range of mathematical learning activities. Included were group and pair tasks designed specifically to encourage meaning-making talk to enhance students' use of mathematical language. The ongoing, grounded analysis revealed two distinct aspects of language use in the mathematics classroom. The first was the "opportunity to speak"--the space and invitation given for students to articulate and modify their thoughts about mathematical tasks through speech. The second identified aspect was the "mean to speak"--students' understanding of mathematical concepts and their ability to use the mathematical terminology intrinsic to them. Qualitative data from the study are used to differentiate between two aspects of language use and indicate advantages of attending to both within the context of adult mathematics learning. Results indicate that curriculum planning in adult mathematics classes should take into account increasing students' communicative competence. The study demonstrates that rehearsal for a larger audience, the need to express thoughts during collaborative tasks, and the need to contribute to written reflections provide students with greater opportunities to speak than traditional mathematics pedagogy. These tasks also awaken in students an interest in acquiring mathematical language. (KHR)