Measures in healthcare that are both reliable and valid serve many masters: optimal clinical care, definable changes and outcomes, clinical research, health administration, quality assurance and system funding. We need better measures, particularly in the area of mental health. The development and subsequent piloting of the Resident Assessment Instrument - Mental Health (RAI-MH) has been described in the preceding article; this commentary is written from the perspective of a clinician, an academic and a hospital administrator.