Abstract: To advance international mental health assessment, instruments that have been internationally validated are needed. To this end, we analyzed ratings from 14 societies on the Adult Behavior Checklist (ABCL), a collateral-report form parallel to the Adult Self-Report (ASR; Achenbach and Rescorla 2003) for ages 18 to 59. Both the ABCL and the ASR assess problems, personal strengths, and adaptive functioning. For a sample of 8322 see note below collaterals, we found strong consistency across societies regarding which ABCL problem items tended to obtain relatively low, medium, or high ratings. Most societal effect sizes (ESs) for problem scale scores were small to medium (< 13.9 %), but the ES for the ABCL Personal Strengths scale was 25 %. For most of the same participants (N = 8,302), we analyzed cross-informant agreement between self-reports on the ASR and collateral reports on the ABCL. Cross-informant correlations for problem scale scores averaged .47, with considerable societal variation. Problem score means were higher on the ASR than the ABCL in every society, but the size of the difference varied across societies. Mean item ratings on the ABCL and ASR were highly correlated within every society (mean r = .92), but within-dyad item rating agreement varied widely in every society (mean r = .39). In all societies, non-corroboration of self-reported deviance and of collateral-reported deviance was common. Overall findings indicated considerable similarity but also some important differences in collateral-reported problems and adaptive functioning across 14 societies.