We conducted two studies to assess the test-retest reliability of drug treatment questions in the Risk Behavior Assessment (RBA) and Risk Behavior Follow-Up Assessment (RBFA). In Study 1, 218 active drug users participated in an RBA 48-hour test-retest reliability assessment; in Study 2, 257 active drug users participated in an RBFA 48-hour test-retest reliability assessment. Results revealed acceptable reliability for the main drug treatment question in both the RBA (.85) and RBFA (.85): "Have you ever in your lifetime been in a drug treatment or detoxification center?" Other more specific drug treatment questions yielded mixed results. Twenty-four of the 35 RBA and RBFA treatment variables (68.6%) that could be calculated displayed acceptable test-retest reliability coefficients. Test-retest reliability coefficients for the RBFA continuous variables could not be calculated owing to a lack of participants in drug treatment during the previous 6 months. Future research establishing greater delineation of this problem may aid in the construction of assessment instruments.