Multistage testing (MST), an adaptive test delivery mode that involves algorithmic selection of predefined item modules rather than individual items, offers a practical alternative to linear and fully computerized adaptive testing. However, interactions across stages between item modules and examinee groups can lead to challenges in item calibration with MST. This study used simulated data based on an operational program to investigate the performance of four item calibration methods under a 1-3 MST design. Conditions included routing module length, routing rule, and sample size. Calibration methods were evaluated based on item and person parameter recovery and classification accuracy. Results indicated that calibration with fixed common item parameters and concurrent calibration assuming a single ability distribution similarly outperformed both separate calibration with linking and concurrent calibration with the multiple-group procedure.