The OECD changed the mode of delivery in PISA 2015 from a paper-based assessment (PBA) to a computer-based assessment (CBA). In PISA 2015, four countries improved their results in all three tested domains, and three of these were Nordic countries (Denmark, Norway, and Sweden). Students in the Nordic countries have significant experience in using digital devices, and this might be a plausible explanation for the improved results. In line with this, the results from South Korea and Turkey, two countries with a low average use of computers and the Internet, deteriorated when the test mode was changed. It is of vital importance to ensure that the PISA results from the computer-based test are comparable to previous results if countries are to make policy decisions based on the results. The overarching purpose of the present study is to explore how the change from PBA to CBA was associated with the Nordic students’ performance on the reading tasks in PISA in relation to item format, gender, computer experience, and the three reading aspects that were assessed. The analysis was performed on the overall results in reading literacy as well as the specific items that were used in both PISA 2012 and PISA 2015, in all the Nordic countries. Among the Nordic countries, there were no dramatic changes in the results on reading literacy in PISA 2015 compared to PISA 2012. Only in Sweden was a major 124Northern Lights on TIMSS and PISA 2018change observed. Our findings show that in comparisonwith the other Nordic countries, Sweden seems to have a larger group of students who spend large amounts of time on the Internet, and this group improved their results on PISA 2015 compared with PISA 2012 more than other groups in Sweden and more than similar groups in the other Nordic countries. All of the Nordic countries showed a decreased proportion of students who gave no response to items and who did not complete all items in the PISA test on reading literacy. At the same time, the proportion of full-credit responses and no-credit responses increased.