To maintain the validity of a continuous testing system, such as computerized adaptive testing (CAT), items should be monitored to ensure that the performance of test items has not gone through any significant changes during their lifetime in an item pool. In this article, the author developed a sequentially monitoring procedure based on a series of statistical hypothesis tests to examine whether the statistical characteristics of individual items have changed significantly during test administration. Simulation studies show that under the simulated setting, by choosing an appropriate cutoff point, the procedure can control the rate of Type I errors at any reasonable significance level and meanwhile, has a very low rate of Type II errors.