We conducted a reliability-generalization meta-analysis of 7 of the most frequently used measures of relationship satisfaction: the Locke-Wallace Marital Adjustment Test (LWMAT), the Kansas Marital Satisfaction Scale (KMS), the Quality of Marriage Index, the Relationship Assessment Scale, the Marital Opinion Questionnaire, Karney and Bradbury's (1997) semantic differential scale, and the Couples Satisfaction Index. Six hundred thirty-nine reliability coefficients from 398 articles and 636,806 individuals provided internal consistency reliability estimates for this meta-analysis. We present the average score reliabilities for each measure, characterize the variance in score reliabilities across studies, and consider sample and study characteristics that are predictive of score reliability. Overall, the KMS and the LWMAT appear to be the strongest and weakest measures, respectively, from a reliability perspective. We discuss the importance of considering reliability invariance when making cross-group comparisons and provide recommendations for researchers when electing a measure of relationship satisfaction.