Available occupational therapy assessment scales focus on specific areas of functioning. There is a need for comprehensive evaluation of diverse aspects of functioning in people with mental illness.

To develop a comprehensive assessment scale to evaluate diverse aspects of functioning among people with mental illness and to assess its validity and reliability.

Available instruments, which evaluate diverse aspects of functioning in people with mental illness, were retrieved. Relevant items, which evaluate specific functions, were selected by a committee of mental health experts and combined to form a comprehensive instrument. Face and content validity and feasibility were assessed and the new instrument was piloted among 60 patients with mental illness. The final version of the instrument was employed in 151 consecutive clients, between 18 and 60 years of age, who were also assessed using Global Assessment of Functioning (GAF), Occupational Therapy Task Observation Scale (OTTOS), Social Functioning Questionnaire (SFQ), Rosenberg Self Esteem Scale (RSES) and Pai and Kapur Family Burden Interview Schedule (FBIS) by two therapists. The inter-rater reliability and test–retest reliability of the new instrument (Vellore Occupational Therapy Evaluation Scale (VOTES)) were also evaluated.

The new scale had good internal consistency (Cronbach’s alpha = .817), inter-rater reliability .928 (.877–.958) and test–retest reliability .928 (.868–.961). The correlation between the general behaviour domain (Pearson’s Correlation Coefficient [PCC] = –.763, p = .000), task behaviour (PCC = –.829, p = .000), social skills (PCC = –.351, p = .000), intrapersonal skills (PCC = –.208, p = .010), instrumental activities of daily living (IADL) (PCC = –.329, p = .038) and leisure activities (PCC = –.433, p = .005) scores of VOTES with the corresponding domains in the scales used for comparison was statistically significant. The correlation between the total score of VOTES and the total scores of OTTOS, SFQ and RSES was also statistically significant suggesting convergent validity. The correlation between the total score of VOTES with the total score of FBI is not statistically significant, implying good divergent validity.

VOTES seems to be a promising tool to assess overall functioning of people with mental illness.