The recent surge in anti-trans laws and policies in Canada and the United States has important public health implications, particularly for trans and gender-expansive (TGE) youth. This legislation has the potential to exacerbate minority stress experienced by TGE youth, who already experience higher rates of depression, anxiety, and suicide than their cisgender peers. Social gender affirmation, including respecting affirmed names and pronouns, can reduce the risk of adverse mental health outcomes in TGE youth. However, recent laws requiring parental consent for affirmed names and pronouns in schools can cause additional distress and harm for TGE youth, especially those who lack family support. Public health professionals have a critical role to play in countering the harmful effects of anti-trans legislation by better understanding TGE youth and their needs, advocating for trans rights, supporting trans-led community organizations, and strengthening trans-affirming mental health services.