Advocacy carries the potential for LGBTQ+ youth (e.g., lesbian, gay, bisexual, transgender, and queer youth) to have a voice against injustice, even while carrying potential risks, yet limited research has identified factors that correspond with their engagement in it. This study utilized three waves of data from 48 school-based Gender-Sexuality Alliances (GSAs) to consider whether taking on GSA leadership roles, victimization experiences, sexual orientation identity outness, gender identity outness, and positive self-image were associated with and predictive of advocacy over the school year. The sample included 181 cisgender LGBQ+ youth (50.8% youth of color; Mage = 15.12 years, SD = 1.74) and 271 trans/nonbinary LGBQ+ youth (49.4% youth of color; Mage = 15.04 years, SD = 1.51). Cisgender LGBQ+ youth reported greater advocacy during periods when they took on more GSA leadership; also, those who, on average, took on more leadership than others reported greater advocacy over the study period than others, as did those who reported greater sexual orientation identity outness and a more positive self-image at the beginning of the study. Trans/nonbinary LGBQ+ youth reported greater victimization and greater leadership during periods when they reported greater advocacy; those who, on average, took on more leadership than others reported greater advocacy over the study period, whereas greater gender identity outness at the beginning of the study predicted lower advocacy over the study period. These findings carry implications for how GSAs could facilitate LGBTQ+ youth’s advocacy while attending to different barriers or support needs among youth.