The function of mental health service is to improve the welfare of clients and, by extension, the general population. Evidence indicates that such benefits exist, but also that some individuals are negatively affected by certain interventions, programs, diagnoses, “preventive” measures, and public education campaigns. One way to improve overall outcomes is to sharpen the positive effects of what we do; another - often neglected - is to examine the failures in mental health history and determine how to avoid making such errors in future. Presentation for the Clinical Psychology program of the Department of Psychology at University of British Columbia.