This paper investigates how horizontal and vertical individualism and collectivism predict self-report loneliness in addition to the variance accounted for by age and sex in 28 countries ( N = 8,345).Horizontal and vertical aspects of individualism and collectivism had small but significant contributions to predicting loneliness.Horizontalcollectivism (for 19 country samples) and, to a lesser extent, horizontal-individualism (for seven country samples), significantly predicted lower loneliness scores.Vertical-individualism (for 16 country samples), and to a lesser