Computerized adaptive testing (CAT), which was first developed four decades ago, begins with a large pool of questions and then selects individual questions for test takers, depending on their responses as they progress. As the test taker answers questions correctly, the questions become more difficult. As the test taker answers incorrectly, the questions become less difficult. CAT requires the following components: a pool of questions to draw from, calibrated to a common measurement scale; a mechanism to select questions on the basis of students' responses; a process to score students' responses; a process to terminate the test; and reports that relate students' scores to their instructional needs. This update identifies the benefits and limitations of using computerized adaptive assessments, and considerations for states and districts interested in implementing computerized adaptive assessments.