© 2015 Elsevier Ltd.Objectives: To adapt the trunk stability test to facilitate further sub-classification of higher levels of core stability in athletes for use as a screening tool. To establish the inter-tester and intra-tester reliability of this adapted core stability test. Design: Reliability study. Setting: Collegiate athletic therapy facilities. Participants: Fifteen physically active male subjects (19.46 ± 0.63) free from any orthopaedic or neurological disorders were recruited from a convenience sample of collegiate students. Main outcome measures: The intraclass correlation coefficients (ICC) and 95% Confidence Intervals (CI) were computed to establish inter-tester and intra-tester reliability. Results: Excellent ICC values were observed in the adapted core stability test for inter-tester reliability (0.97) and good to excellent intra-tester reliability (0.73-0.90). While the 95% CI were narrow for inter-tester reliability, Tester A and C 95% CI's were widely distributed compared to Tester B. Conclusions: The adapted core stability test developed in this study is a quick and simple field based test to administer that can further subdivide athletes with high levels of core stability. The test demonstrated high inter-tester and intra-tester reliability.