Background: The South Oaks Gambling Screen (SOGS) is one of the most widely used screening instruments for evaluating addiction to gambling. Method: The main objective of this study is to analyze whether the SOGS is a reliable instrument and what characteristics of studies on the SOGS are linked to its reported reliability. Results: A meta-analysis was carried out with 63 studies including 65 independent samples. The mean value of a was .86 (95% CI of .84-.88), with high heterogeneity (I2 = 98.27%). The variables that explain the most heterogeneity were the continent where the study was performed (R2 = .61), application to participants with or without clinical problems (R2 = .58), the form of administration of the questionnaire (R2 = .56), and the standard deviation in the SOGS score (R2 = .13). Conclusions: The results show that the SOGS is a reliable instrument for evaluating gambling addiction. However, the meta-analysis highlights the need to report the reliability values for each empirical study and to provide a set of recommendations for researchers and professionals who use this instrument