The bullying of sexual and/or gender minority youth at school is a social violence issue that is ubiquitous in most countries. In line with evidence-based practice, teachers are consistently shown to be a critical component of success when addressing this issue; however, teachers' preparedness to respond to sexual and/or gender motivated bullying is under researched. Utilizing components of the theory of planned behavior, a sample of 437 Australian teachers were investigated to determine whether knowledge, perceived barriers, and attitudes toward both sexual and/or gender minorities predicted teachers' intentions to intervene when a sexual and/or gender minority student is bullied above and beyond sociodemographic factors associated with prejudice. Results of hierarchical linear regression demonstrated that teachers with more positive views of gender minorities and less traditional views related to gender ideologies were more likely to endorse higher intentions to intervene in sexual and/or gender minority motivated bullying. Findings suggested teachers' attitudinal biases inform their professional practices when a sexual and/or gender minority student is bullied.