Language demography is the practice of counting speakers of different languages. It is a common discourse technique used when discussing Indigenous languages around the world. However, there is much debate and controversy over how language demography should be practiced, to produce accurate numbers of speakers, and to produce data that is relevant and useful to those working in Indigenous language revitalisation. Alongside this debate on language demography, recent years have seen the emergence of the Indigenous Data Governance (IDG) movement. The IDG movement asks researchers to address the historical wrongdoings against Indigenous people for the sake of ‘research’, by ensuring Indigenous people have control over the research they are a part of, and access to the data that comes from that research. Indigenous organisations and researchers working within IDG frameworks argue that giving Indigenous people control of research processes concerning them, and the ability to own and freely access their own data, produces data that is more accurate, relevant, and useful to Indigenous people. The language demography debate and the IDG movement have proceeded entirely separately until this dissertation. This dissertation examines six demographies of First Nations languages in the Yukon through the lens of IDG principles, to discover how IDG influences the data collected in language demographies, within the unique context of the First Nations self-governance movements of the Yukon. It is the first study to examine the intersection of language demography and IDG. A combination of document analysis of the methodology of different language demographies, data analysis of the demographies, and attempts at interviews with language revitalisation experts working in the Yukon are used. It is found that incorporating principles of IDG into the methodology of language demographies from the start changes the nature of the data that they collect; what data is collected (who counts as a speaker?), how it is collected (who counts the speakers?), and how the data is accessed and stewarded. Incorporating IDG into language demographies produces data that is more accurate, relevant, and useful to First Nations communities. This is because IDG empowers communities to collect the data that is most relevant for their priorities, reduces the harmful effects of extractive research, and enables communities to have free access to their own data. However, there also exist significant barriers to the full implementation of IDG in language demographies. The future of language demography in Indigenous communities must work to dismantle those barriers and to incorporate principles of IDG.