To address the complexity of global challenges (e.g., migration, climate change), research must examine many constructs and their interrelationships. Therefore, efficient assessment methods (e.g., short scales) are required, especially when constructing large-scale social surveys. A widely used instrument for assessing global identification as an important predictor of behavior related to coping with global challenges is the Identification With All Humanity (IWAH) scale (McFarland et al., 2012). With the present study, we aimed to investigate whether this scale can be sufficiently represented by a single item. Using bifactor-(S*I − 1) models, we analyzed whether one item from the scale itself (Item 5) and a related single-item measure from the World Values Survey (WVS; Inglehart et al., 2018) could adequately represent a German version of the IWAH scale. The sample (n = 1,369) was representative of the German population regarding age, gender, income, education, and region of residence. Item 5 showed an appropriate single-item reliability (.82) and represented 64–93% of the true variance in the individual IWAH items, whereas the WVS item (Rel(YWVS) = .61) represented 52–81%. To reflect the multidimensionality of the IWAH, a 4-item short scale is recommended.
