The present study uses city, state, cross-national, & time series data to assess the criterion validity of over 2 dozen gun indicators. The criterion measures used are primarily direct survey measures of household gun prevalence. The results indicate that (1) most measures used in past research have poor validity, making past findings uninterpretable, (2) the best measure for cross-sectional research is the percentage of suicides completed with guns, & (3) there are no known measures that are valid indicators of trends in gun levels. (65 refs)