The objectives of the study were as follows: To gather evidence on the nature, scale and impact of bullying targeting students who are or are perceived to be same-sex attracted or transgender, attending general secondary schools in 5 provinces of Thailand; To study various aspects of the lifestyles of secondary school students that might be linked to bullying behaviours; To document the availability of existing prevention and support interventions on bullying targeting students who are or are perceived to be same-sex attracted or transgender, including accountability measures for those perpetrating bullying; and To assess the support and educational needs of same-sex attracted and transgender secondary school students; as well as the training needs of teachers in the area of effective bullying prevention.