 The intervention will be administered, alongside TAU, to inpatients at a BIRT centre in Glasgow and will be compared to a comparison group which will receive TAU only who will be based in BIRT centres in either York andor Leeds. The rational for choosing a BIRT centre in Glasgow for the intervention group is one of convenience as all researchers involved in the study are based in Glasgow. This will help facilitate data collection and reduce cost. Given that all BIRT centres adhere to a similar philosophy of care and rehabilitation and service user profiles are relatively similar, it was believed that recruiting elsewhere for the purpose of comparison would be appropriate. Recruiting treatment and comparison groups from separate centres also ensures that clients receiving TAU only do not learn ACT strategies accidentally through discussion with peers or staff. If this were to happen any indication of change could not be attributed to the difference in treatments provided. 