Lead author Susan Swearer of the University of Nebraska-Lincoln and colleagues tracked more than 800 special-education and general-education students ages 9-16 at nine elementary, middle and high schools over time.
The study, published in the Journal of School Psychology, found 67 percent said bullies had victimized them, while 33 percent said they had not. However, the researchers also found 38 percent of the special-ed students said they had bullied other students.
In particular, students with observable disabilities -- language or hearing impairments or mild mental handicaps -- reported the highest levels of bullying others and being bullied themselves.
"The observable nature of the disability makes it easy to identify those students as individuals with disabilities, which may place them at greater risk for being the easy target of bullying," Swearer said in a statement. "Also, being frustrated with the experience of victimization, those students might engage in bullying behavior as a form of revenge."
Students with non-observable disabilities, such as a learning disability, weren't affected as much, Swearer said.
"These results paint a fairly bleak picture for students with disabilities in terms of bullying, victimization and disciplinary actions," Swearer, a national expert on school bullying who has consulted with the White House and Lady Gaga's Born This Way Foundation on anti-bullying initiatives, said in a statement.