C-Tests are widely used as tests of general language proficiency in foreign language assessment and research. C-Test is reported as a reliable measure with reliability indexes of 0.80 and above. However, in most studies only Cronbach’s alpha reliability has been reported. In this research, we aim to examine the reliability of C-Test with other methods of estimating reliability. To achieve this, three different datasets from previous studies were employed to investigate the reliability of   C-Test with different methods. Eight methods of estimating reliability, namely, Cronbach’s Alpha, split-half, Guttman, parallel forms, omega, MS (rho), Lambda-2, and LCRC, were applied to evaluate the reliability of the C-Tests. Findings showed that C-Tests are highly reliable and different methods yield similar results. The findings of this study support the high reliability of C-Tests.