'Behaviour can be described as challenging when it is of such an intensity , frequency or duration as to threaten the quality of life and/or the physical safety of the individual or others and it is likely to lead to responses that are restrictive, aversive or result in exclusion'.

Source: Royal College of Psychiatrists, British Psychological society, Royal College of Speech and Language Therapists, (2007).  Challenging Behaviour - A Unified Approach.

If you need help/support with regards challenging behaviour then you can refer to your local  Community Learning Disability Team

Behaviour Recording Chart
How to fill in a behaviour recording chart
Setting events checklist