The University of California, Los Angeles, Loneliness Scale-Version 3 (UCLA LS3) is the most frequently used loneliness assessment tool. This study aimed to examine the psychometric properties of the UCLA LS3 by utilizing two separate and independent samples: Turkish university students (n = 481) and elderly (n = 284). The results demonstrate that the 3-factor model reveals significant results in both samples in terms of goodness of fit indices in confirmatory factor analysis. In addition to satisfactory reliability, the concurrent and discriminant validity of the scale were supported in both samples by revealing the association of the UCLA LS3 with conceptually related measures (i.e., social support, social provision, depression, positive affect, negative affect, and self esteem in the sample of university students; geriatric depression, self esteem and life satisfaction in the sample of elderly) and the unrelated measure (i.e., social desirability). In addition to examining the psychometric properties of the UCLA LS3, the present study adds to the present literature about loneliness, shedding light on a non-western culture. (Contains 3 tables.)