Despite prolific use of the term 'blended learning' in tertiary institutions, agreement on a definition remains elusive. The definitions and understandings of the concept are many (Driscoll, 2002; Vignare, 2007) and often offer little pedagogical direction. This is problematic. Under the umbrella of so many definitions almost any teaching practice can be viewed as blended learning. In the absence of pedagogically focused definitions it is difficult to designate the nature of implementation, measure success and provide appropriate institutional support. This paper attempts to help address these issues and so contribute to the fulfilment of the promise of blended learning. The definitions of blended learning in literature and across twenty Australian universities are explored. Against this background, drawing on principles of constructivism, constructivist alignment (Biggs & Tang, 2007) and universal design for learning, a definition of blended learning is proposed. An accompanying planning approach is presented. At the crux of the planning approach is framing blended learning, not as an exercise in technology use but rather as a problem solving exercise, directed at how best to engage diverse groups of learners in learning activities (Shuell, 1986) in order to maximise opportunities for achievement of desirable outcomes. Implicit in this view is the importance of reflective practice as the driving force for continuously improving blended designs.