We evaluated the independent association between adaptive behavior, communication and repetitive or ritualistic behaviors and self-injury, aggression and destructive behavior to identify potential early risk markers for challenging behaviors. Data were collected for 943 children (4–18 years, M = 10.88) with severe intellectual disabilities. Odds ratio analyses revealed that these characteristics generated risk indices ranging from 2 to 31 for the presence and severity of challenging behaviors. Logistic regressions revealed that high frequency repetitive or ritualistic behavior was associated with a 16 times greater risk of severe self-injury and a 12 times greater risk of showing two or more severe challenging behaviors. High frequency repetitive or ritualistic behaviors independently predict challenging behavior and have the potential to be early risk markers for self-injury and aggression of clinical significance.