BackgroundIndividuals’ concealment of negative information and privacy may lead to impaired social interactions and threatened health conditions. This study aimed to investigate the effectiveness of the Self-Concealment Scale (SCS) in the middle-aged Chinese population and to examine the equivalence of the SCS among different age groups.MethodsThe current research adopted the SCS, Distress Disclosure Index (DDI), Revised Cheek and Buss Shyness Scale (RCBS), Social Interaction Anxiety Scale (SIAS), Social Phobia Scale (SPS), UCLA Loneliness Scale (ULS-8), and Kessler Psychological Distress Scale (K10) to survey 1124 middle-aged people. To explore the factor structure of the SCS, the study employed exploratory factor analysis and confirmatory factor analysis. The reliability of the SCS was measured based on Cronbach’s α coefficients, McDonald’s Omega coefficients, and split-half reliability. Correlation analysis was applied to examine the relationship between SCS and RCBS, SIAS, SPS, ULS-8, and K10. Moreover, this study recruited 1458 emerging adults and 1104 older adults to identify the cross-age invariance of the SCS.ResultsExploratory factor analysis of the middle aged adults’ data supported a single factor model. The factor loadings of SCS items ranged from 0.62 to 0.73, the commonality ranged from 0.39 to 0.53, and the single-factor model fitted well. The scale showed a Cronbach’s α coefficient value of 0.895, McDonald’s Omega coefficient of 0.893, and a split-half reliability coefficient value of 0.861. In addition, the SCS demonstrated invariance in emerging adults, middle-aged adults, and older adults. Further analysis showed that the scores of the SCS (F = 3.55, p = 0.029) among emerging adults (M = 26.43, SD = 7.96) were significantly higher than among middle-aged (M = 25.77, SD = 7.79), and older cohort (M = 25.69, SD = 7.91).ConclusionThe SCS revealed favorable psychometric characteristics among the middle-aged Chinese population. The degree of self-concealment among emerging adults was higher than that of middle-aged and older people.