In this study, a 4-item battery of core stability (CS) tests modeled on core stabilization activities used in training and rehabilitation research was developed, and a measurement schedule was established to maximize internal consistency and stability reliabilities. Specifically, we found that 4 test administrations on each of 4 days produced intraclass correlation coefficients that in most instances exceeded 0.90 and stability reliability coefficients on the third and fourth days of testing that exceeded 0.90 for 2 of the tests and 0.80 for the other 2. Thus, it is recommended that in future research, examiners administer the battery for at least 3 days and consider the data collected on day 3 as the best estimate of participant CS.