This thesis investigates the teaching of statistical literacy in the first two years of secondary school mathematics. The teachers involved in the research aim to make changes to classroom practice in the teaching and learning of statistics and statistical literacy in response to changes in the New Zealand curriculum. An action research methodology is adopted by the research. A group of three teachers and the author undertake an action research cycle of planning, observing, acting and reflecting in three different Year 9 and 10 mathematics classrooms. The research documents the designing and implementing of strategies by a group of teachers in a mathematics department for integrating statistical literacy into teaching programmes. The research adopts framework for improving practice that utilise models for statistical literacy and thinking and principles for teaching with a language learning or literacy focus. Data is collected through discussions with teachers, observations of lessons and interviews with teachers and students. Themes emerge from the data. They include the significance of teacher and student concepts of statistics and statistical literacy, the importance of language and literacy in the statistics classroom, the adoption of teaching principles to facilitate statistical literacy and the challenge of adopting a critical literacy stance in the statistics classroom. The study highlights the importance of literacy and language skills in statistical literacy. The research concludes that the important changes needed for developing statistical literacy are about classroom methodology rather than content knowledge and shows that adoption of language learning principles into the teaching programme may achieve this.