This paper presents the results of a study designed to assess the representativeness of realized samples of recent arrestees selected for the Arrestee Drug Abuse Monitoring (ADAM) program in Anchorage, Alaska. Because one of the most important goals of the ADAM program is to produce scientific information on the prevalence of alcohol and drug use behaviors among arrestees that is generalizable to an entire local arrestee population, establishing the representativeness of realized samples (or isolating inherent biases) is an essential first step to meaningful use of these data to address locally defined problems. In order to determine the reasonableness of inferences grounded in realized samples of ADAM respondents, an analysis was done comparing various characteristics between each stage of the sample selection process including the census of eligible arrestee population, the designed ADAM arrestee sample, arrestees available for interview, arrestees actually interviewed (“realized” sample), and arrestees that provided urine sample (“realized” sample). If the realized samples are similar to the census we can have a greater degree of confidence in our capacity to describe the population of Anchorage arrestees using ADAM data. Also, if it happens that departures are detected between realized samples and the arrestee census we are better positioned to condition the inferences made by integrating these discerned biases into our conclusions.