This chapter defines, describes, and assesses the form of collaborative virtual learning environment known as MOOs. MOOs offer opportunities impossible in any other actively developed online communication tool, but they have remained largely the purview of hackers, coders, and academics. This chapter deals with understanding what a MOO is, what key features make it a valuable collaborative environment, and issues of accessibility, access, and governance. Key aspects include defining and historicizing MOO, exploring the technology’s current development, discussing issues that presently limit large-scale acceptance, and speculation about the possibilities and the future of MOO. The chapter considers text-based multimedia environments; general features of synchronous and asynchronous technologies; the notion of polysynchrony; tools for rapid prototyping, education, or training of users; application accessibility; costs in hardware, software, and manhours; and whether it’s worth organizations getting involved in MOOs at their present state of development.