Design is an inverted discipline. The concept of rigour, as understood within the natural sciences, cannot be applied to Design Practice. Rigour for the natural sciences is a quality assurance mechanism ensuring that the knowledge bases of the disciplines are developed to an accepted set of standards. Design’s ontology is not like the natural sciences and as such an understanding of rigour for Design must proceed from an appropriate standpoint about the nature of Design Practice. This paper builds upon Harfield’s  ontological assessment of Design, Schön’s   work on Reflective Practice and Spencer’s  investigation into the experience and practise of designing to develop a standpoint about Design Practice and make a proposition about the relevance of rigour for Design Practise. This paper considers how individual Reflective Practice practitioners, within the context of Design Practice, manage and ensure quality control through the application of care and thoroughness. This paper argues that rigour for Design Practise is the personal and phenomenological quality control of a design inquiry: a process of managing expanding mental chaos and restricting order.