As massive open online courses (MOOCs) increase, the large scale and heterogeneity of MOOC participants bring myriad significant design challenges. This mixed methods study explores 143 MOOC instructors’ considerations and challenges in designing MOOCs; 12 of whom were interviewed and had their courses analyzed. The survey, interview, and course review data revealed a variety of considerations and challenges in MOOC design in terms of pedagogy, resources, and logistics. Pedagogical considerations included learning objectives, assessment methods, course length, course content, flexibility, and collaborative learning support. Resource considerations included the affordance of MOOC platforms, support from the host institution and the platform, and the available intellectual and hardware resources. Logistical considerations included the amount of time instructors spent designing the MOOC. The obstacles included pedagogical challenges (engaging students, increasing student interaction, and limited assessment methods), resource challenge (i.e., limitations associated with the affordances of the platform), and logistical challenge (time limitations for designing and developing MOOCs). To address these challenges, the instructors often relied on reviewing other MOOCs. They also sought help from colleagues, their universities, and supporters of the platforms.