A MOOC is a trending concept in education that is disrupting traditional methods oflearning consumption. The emergence and use of MOOCs for professional teacher development isstill uncommon, but on the verge of gaining a foothold. Research regarding MOOCs typicallyfocuses on impacts for higher education and lifelong learning. However, the specific intersection ofMOOCs and professional teacher development is poorly researched. This concept papercontemplates the benefits and drawbacks of using MOOCs for professional teacher developmentand calls for more practical studies and explorative research. This paper also speculates on the basicMOOC design criteria and principles needed to maximize engagement and course completion,which are currently common issues with general MOOCs. The conclusion is that MOOCs can be acost- and resource-effective means to deliver quality education in order to further professionalteacher development. However, possible risks are employers' reluctance to accept MOOCaccreditation as equivalent professional development and the lack of relevant MOOC courses forprofessional development.