Teacher activism is developing throughout the country with an expanding research base, but little research addresses teacher activism specifically in STEM fields. Using critical race feminism, intersectionality, and TribalCrit this qualitative study focuses on four STEM teacher activists, who founded a social justice STEM organization, to explore how they became involved in grassroots organizing and how they conceptualize STEM teacher activism (STA). Findings indicate that firsthand experiences of marginalization sparked their engagement in teacher activism and that participants have a strong understanding of structural oppression. STA becomes a vehicle for their own healing as well as a means toward addressing the inequities they witness and experience in their communities. Participants define STA as attending to community health and ancestral knowledge to humanize STEM education for their communities.