A short quiz of Addiction Severity Index (ASI) coding conventions was developed to identify coding inconsistencies within a large group of trained interviewers, as one step in an overall program of quality assurance monitoring. Problem items, in which less than 75% of the quiz respondents answered correctly, existed in almost every ASI section. The ASI quiz has proven helpful in identifying "drift" from the ASI standard procedures. Individually reviewing the results of the quiz with the respondents helped to reinforce the recognized coding rules. The authors discuss a system-wide quality assurance program for maintaining interviewer consistency. It is believed that coding convention measures of this type could be useful in the maintenance of standards in other research interviews and procedures.