In the last 10 years a sum in excess of 200 million pound has been spent in developing a new programme of treatment for those deemed to have dangerous and severe personality disorder (DSPD) in England. This proto-diagnosis is a new concept in forensic psychiatric practice and, although its conception was bold, it carried considerable risks in implementation as so little was known about the effective management of this group of disorders. We review the successes and failures of this pioneering programme a decade after its introduction and conclude that although much has been gained from the experiment--particularly in developing services for those with personality disorder in general--it has been less effective in managing those whom it was primarily targeting and may not have been cost-effective.