This paper analyzes measurement errors in crime data to see how they impact econometric estimates, particularly of the key relationship between inequality and crime. Criminal victimization surveys of 140,000 respondents in 37 industrial, transition and developing countries are used. Comparing the crimes experienced by these respondents with those reported to the police, non-random and mean-reverting measurement errors are apparent. Some time-varying factors may also affect the propensity of victims to report crimes to the police, undermining the use of country-specific fixed effects as a means of dealing with measurement errors in official crime data. These measurement errors substantially attenuate both cross-sectional and panel estimates of the effect of inequality on crime.