Aggression and stereotyped behaviors are not uncommon among people with intellectual disabilities and they are often treated separately as operant behaviors. In this single case study, it is argued that the function of a young woman's aggressive behavior appeared to be that of avoiding or escaping the termination of a chain of complex stereotyped behavior (or "ritual"). She became aggressive only when this chain of stereotyped behavior was terminated and the aggression appeared to extinguish when it no longer led to escape from the termination of the "ritual". It is suggested that this is an example of a complex interaction between two behaviors and that it illustrates the need for very careful analysis of the functions of challenging behavior. Furthermore, it is proposed that the lengthening list of variables already documented as determinants of challenging behavior (provision of attention (verbal and physical), mechanical restraint, sensory or tangible events, escape from demands or from social attention, denials, escape from intrusive medical procedures, escape from task difficulty) be lengthened to include the possibility of escape from (or avoidance of) the interruption of a chain of complex stereotyped behavior or "ritual".