Background: Seattle Public Schools has implemented policies and programs to increase safety, family involvement, and student achievement for lesbian, gay, bisexual, transgender, and questioning (LGBTQ) youth. This case study examines students' perceptions of bullying and harassment in the school environment, and teacher intervention when these problems arise in the presence of strong district policies and programs aimed at reducing LGBTQ bullying and harassment in schools. Methods: We surveyed students in Gay-Straight Alliance (GSA) groups at 13 secondary schools (N?=?107). We also conducted focus groups with GSA students and students not involved in the GSAs in 7 of 13 schools (N?=?16 groups, including 154 students). Results: GSA students who were lesbian, gay, bisexual, or questioning (LGBQ) were significantly more likely than straight students to experience several types of harassment. On the basis of student report, the 2 most common intervention strategies by teachers for verbal harassment included stopping the harassment and explaining why it is wrong; teachers intervened in physical harassment by trying to stop the harassment. Students provided input on how to strengthen teacher interventions, including the need for more consistency in responding and following up. Students also noted a need for more focus on educating those who harass, rather than just asking them to stop. Conclusions: Seattle Public Schools has made great strides in creating safe and welcoming schools for LGBTQ students, but still have to work further toward reaching this goal. Data from students on how they experience their school environment can help identify areas for improvement.