A study was conducted to explore the beliefs and practices of 49 New South Wales (NSW) primary school teachers regarding their beliefs and practices concerning the use of concrete materials in the learning and teaching of Number and Algebra. This paper reports on elements of the study regarding why and how teachers use concrete materials. Not only do teacher beliefs influence their classroom practice, Buehl and Beck (2014) propose that teacher practices may impact teacher beliefs suggesting they are interrelated. This paper sought to situate teacher beliefs and practices upon a conceptualisation of this interrelationship based on aspects of classroom practice involving concrete materials. The study employed survey methodology utilising a questionnaire and semi-structured interviews to gather data that were analysed to identify key themes regarding teachers' prevailing beliefs about the use of concrete materials. These themes included a belief in a social constructivist approach to learning and teaching mathematics, a cognitive dimension and engagement. On the basis of these findings an overview is suggested that positions teacher beliefs and practices relating to the use of concrete materials and how it might be used to shift inservice and preservice teachers' beliefs towards a more constructivist teaching approach.