Critical thinking is a graduate attribute that many courses, including engineering courses, claim to produce in students. As a graduate attribute it is seen by academics as a particularly desirable outcome of student learning and is said by researchers to be a defining characteristic of university education. However, how critical thinking is understood and defined varies quite significantly between disciplines. The paper describes a series of in-depth, semi-structured interviews with academics involved in teaching and learning in a number of disciplines, including engineering. The objective of these interviews is to look at how different disciplines define critical thinking and how they teach critical thinking in their courses. The paper also describes how an analysis of student work and module descriptors has led to the development of a model of critical thinking that can be used across disciplines. (Contains 2 tables.)