Although large-scale national tests have been used for many years in Swedish compulsory schools, very little is known about how pupils actually react to these tests. The question is relevant, however, as pupil reactions in the test situation may affect test performance as well as future attitudes towards assessment. The question is relevant also in light of the changing assessment culture in Sweden and other European countries. The main purpose of the present study was to explore how a sample of grade 9 pupils perceived their first encounter with national tests in science, mainly in terms of perceived importance of the test, reported invested effort, and feelings of test anxiety, and how these aspects were related to test performance. Results show that a majority of the pupils seemed to perceive the test as rather important and claimed that they spent effort on the test. There was, however, also a fair group of students who did not perceive the test as very important. Ratings of perceived importance and invested effort and motivation were positively related to performance, particularly for the boys. Many students also reported that they felt anxious before and during the test, but the relationship between test anxiety and test performance was rather weak. Findings illuminate how pupils may perceive and behave in the assessment situation, and point to the need of further studies investigating the psychology of test-taking.