How do you design a quality massive open online course (MOOC) that will be ‘fit for purpose’? The Understanding Dementia MOOC is an initiative of the University of Tasmania’s Wicking Dementia Research and Education Centre (Wicking Centre). It is an outworking of institutional commitment to open education resources (OER) and open educational practices (OEP). This paper describes the development of the university’s first MOOC, grounded in a philosophy that open learning design includes the criterion ‘fit for purpose’ and thus explicitly considers: the impetus for attempting a MOOC design; the goal (desired outcomes); the nature of the content; assumed capability thresholds of the intended cohort and; the technical and pedagogical design implications of the cohort’s learning readiness. The development team used a design-based research approach underpinned by an evaluation framework. This paper will discuss the interplay of factors which influenced decision-making, including the nature of expert content (packaged by the development team, translated by students and applied in individual contexts), the intended scope of influence, barriers to access in open learning design, pedagogical commitments including adult learning theory, technological constraints, as well as external stakeholder requirements . The paper concludes with a discussion of the impact of maintaining a clear purpose in making a specific body of knowledge available as open content. In particular, we suggest that considerations of content access are not simply physical or technical, but require tailoring the approach to threshold learning capabilities, as well as providing scaffolded content delivery such that individuals can translate their learning for their own contexts.