Aim The main objective of this study was the validation of a brief support instrument for the diagnosis of insomnia in older adults. Methods An observational study was carried out for the evaluation of the Insomnia in the Elderly Scale using the psychiatric interview as the gold standard. Data was collected in a primary care setting in the city of Albacete, Spain. Participants were 926 non‐institutionalized older adults aged ≥65 years. Results Sleep characteristics, and the health and sociodemographic status of the participants were assessed. The Insomnia in the Elderly Scale is divided into two subscales for the evaluation of the Diagnostic and Statistical Manual of Mental Disorders, Fouth Edition criteria A and B for insomnia. The area under the receiver operating characteristic curve for subscale A was 0.868. The cut‐off point to detect the presence of diagnostic criterion A for insomnia was a score of ≥3 (sensitivity: 86.4%; specificity: 69.5%). The area under the receiver operating characteristic curve for subscale B was 0.832. The cut‐off point to detect the presence of diagnostic criterion B was a score of ≥2 (sensitivity: 86.3%; specificity: 66.4%). Conclusions The Insomnia in the Elderly Scale has appropriate psychometric properties. This scale compensates for the lack of validated instruments for use in the population aged 65 years or older. The fact that it is divided into two subscales to separately evaluate the insomnia criteria enables us to detect the presence of each of them. Finally, it has been validated in participants aged 65 years and older, which is the target population for this scale. Geriatr Gerontol Int 2013; 13: 646–653.