The Supreme Court of Canada's decision in Carter v Canada (AG) decriminalized medical aid in dying in certain defined circumstances. One of those circumstances is that the person seeking assistance be an "adult." This article argues that the regulatory response to this decision must approach the idea of "adult" in terms of the actual medical-decisional capacity of any given individual, and not rely upon age as a substitute for capacity. This article surveys jurisdictions where minors are included in physician-assisted dying regimes, and identifies what little empirical evidence exists regarding requests from minors. The heart of the article considers the jurisprudence on mature minors and when they are deemed to have the right to require the withdrawal of, or refuse to receive, life-sustaining treatment, and compares the reasoning in these cases with that in Carter. A particular focus of this article is on how the jurisprudence approaches decisional capacity when the individual in question may be particularly vulnerable. It finds that a blanket exclusion of mature minors from a physician-assisted dying regime likely violates the Canadian Charter of Rights and Freedoms, and calls out for considered debate on these issues instead of forcing a minor and their family to bring the issues forward through litigation.