Objective: This article reports on two separate studies of reliability of the Adolescent Domain Screening Inventory (ADSI), test-retest and internal consistency analyses. The ADSI has shown adequate validity, although reliability has not been established. Methods: Study 1: Students were recruited from two undergraduate courses (N = 29). Participants were administered the ADSI twice, 14 days apart. Data were analyzed using SPSS software; correlations were computed for all four domains and the total score. Study 2: A secondary data analysis of 6,661 cases was conducted using the Scale - Reliability Analysis function in SPSS to determine the Cronbach alpha for each domain in the ADSI. Results: Study 1: Correlations were as follow: Total - r = 0.95; school - r = 0.84; family - r = 0.85; community - r = 0.80; and individual/peer - r = 0.95. Study 2: Alphas were as follow: 0.53 - school, 0.62 - family, 0.55 - community, and 0.82 - individual/peer. Conclusions: Together, these studies provide evidence for the reliability of the ADSI. (Contains 2 tables.)