The study aims to develop three school bullying scales--the Bully Scale, the Victim Scale, and the Witness Scale--to assess secondary school students' bullying behaviors, including physical bullying, verbal bullying, relational bullying, and cyber bullying. The items of the three scales were developed from viewpoints of bullies, victims, and witnesses. Two samples of Taiwanese secondary students participated in the test development, one for item revision and the other for validation. Samples 1 and 2 consisted of 860 and 3,941 students, respectively. Rasch techniques were applied to assess model-data fit of the three scales. The results indicated that the correlations of person measures from viewpoints of bullies, victims, and witnesses were between 0.78 and 0.83; the person separation reliabilities of the measures from the Bully Scale, the Victim Scale, and the Witness Scale were 0.86, 0.87, and 0.94, respectively. The person measures from the three scales were positively correlated with external variables--antisocial behaviors, depression, anxiety, and perception of school safety. The orderings of item difficulties of the three scales were also validated across different samples. (Contains 3 figures and 2 tables.)