Action research has enjoyed increasing popularity across a wide variety of disciplines including nursing. Action research was designed specifically to bridge the gap between theory, research and practice and incorporates both humanistic and naturalistic scientific methods. As such, action research is a highly compelling method for nursing. However, action research does not easily lend itself to definition. A variety of approaches, definitions and uses have emerged since it was created by Kurt Lewin and have given rise to much debate within social and behavioural sciences. This confusion has carried over into nursing literature without any systematic identification of or debate about the core characteristics of action research or the multitude of approaches or uses that have come to be associated with this method. Thus this paper addresses the central characteristics, three major approaches to action research that exist today and how action research has been used and can be used in nursing.