The need for a measure of engagement with Community Mental Health Services has been identified. This article reports on the development and preliminary psychometric evaluation of a scale, Service Engagement Scale (SES), to measure engagement with community mental health services. Five Community Psychiatric Nurses completed the SES for 66 clients receiving Assertive Outreach services with an ICD-10 diagnosis of schizophrenia. Test-retest reliability of the subscale items and scale total is in the good to excellent range. Validity is supported by good internal consistency and by the criterion group method. Although preliminary psychometric results are promising, further psychometric study is necessary to evaluate the scale's factor structure. The SES appears to evaluate engagement with services, and may therefore be a useful tool to identify areas of concern with clients experiencing engagement difficulties.