Rationale and development of a general population well-being measure: Psychometric status of the GP-CORE in a student sample ALICE SINCLAIR & MICHAEL BARKHAM Psychological Therapies Research Centre, 17 Blenheim Terrace, University of Leeds, Leeds LS2 9JT; e-mail: m.barkham@leeds.ac.uk CHRIS EVANS Nottinghamshire Healthcare NHS Trust JANICE CONNELL & KERRY AUDIN Psychological Therapies Research Centre, 17 Blenheim Terrace, University of Leeds, Leeds LS2 9JT ABSTRACT This paper presents the rationale, development, and psychometric status of a non-clinical self-report measure for the general population (GP) / including students  / derived from the Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) and hence termed the GP-CORE. In contrast to the CORE-OM, the GP-CORE does not comprise items denoting high- intensity of presenting problems or risk and thereby increases its acceptability in a non-clinical population. Uniquely, over half the items in the GP-CORE are positively keyed. Analyses showed the GP-CORE to have good reliability, to distinguish between clinical and non-clinical populations, and have convergent validity against the full version. Norms for student populations are presented. It is suggested that the GP-CORE has considerable utility as a means of tapping the psychological well being of students and can then interface with counselling and mental health services using the CORE-OM. Introduction There exists a diverse array of psychological measures of well-being for use in clinical populations (see Maruish, 1999, 2000 for reviews). This plethora of measures, however, has resulted in minimal common usage across studies and led to the observation that there is a ‘state of disarray, if not chaos’ in measuring outcomes from psychological therapies (Froyd et al ., 1996). One response to this situation has British Journal of Guidance & Counselling, Vol. 33, No. 2, May 2005 ISSN 0306-9885/print/ISSN 1469-3534/online/05/020153-21 # 2005 Careers Research and Advisory Centre DOI: 10.1080/03069880500132581