ABSTRACT Background: Loneliness has been associated with physical and mental health problems. It has also been considered a serious social problem that increases the use and costs of health services. The most widely used instrument in Europe for measuring loneliness is the de Jong Gierveld Loneliness Scale (DJGLS). The aim of this study was to examine the psychometric properties of the 11-item DJGLS by means of the Rasch model, and its convergent and discriminant validity. Methods: Participants were a representative sample of Spanish community-dwelling adults aged 60 and older. We evaluated sociodemographic variables, health, social support, social activity, and subjective well-being measures. Results: Person and item fit statistics, and standardized residual principal component analysis revealed that the DJGLS was essentially unidimensional. However, we found DIF across marital status and living arrangements. Moderate to high associations were found between loneliness and depression, self-rated loneliness, positive and negative emotions, and satisfaction with life. The DJGLS differentiated between well known-groups according to gender, marital status, living arrangements, health, structural and functional aspects of social networks, and social activity. Conclusions: The DJGLS is a valid and reliable instrument for measuring loneliness in Spanish older adults. The addition of a few items in order to improve the measurement range is strongly recommended. Our findings are consistent with previous research indicating that loneliness is an important aspect of mental health and subjective well-being, and support the use of the scale to detect vulnerable population in old age.