Since its introduction in 2017, NFER has been contracted by Ofqual to develop, deliver and analyse the results of the National Reference Test (NRT) in English and maths. The NRT is administered annually and shows if student performance in English and maths at GCSE level has changed from year to year. The NRT results are based on analysis of data from a nationally representative sample of secondary schools. The COVID-19 pandemic impacted on the delivery of the 2021 NRT, with the testing window postponed until the summer term. In a normal year, the NRT would be administered in late February/early March. The 2021 NRT took place later and was administered in April/May. There was a smaller sample than in previous years. It should be noted that a slightly higher number of schools were drawn in 2021 to account for the possibility that fewer schools would be able to participate due to the impact of the COVID-19 pandemic. However, the postponement of the test and ongoing impact of the pandemic resulted in many schools being unable to participate in the assessment. Given the lower participation rate for the NRT in 2021, there was more potential for bias in the sample to have an impact on the validity of the outcomes. Therefore additional checks were made on the representation of the sample. The analysis found that, although the precision of the outcomes was reduced by the smaller sample size, the outcomes can still be considered valid. The reduced precision was accounted for by wider confidence intervals around the estimates. The Results Digest provides summarised information of the key performance outcomes for 2021 and comparison with the performance in 2020 at each of the three grade boundaries. Furthermore, it includes more details on the performance of students taking part and the representativeness of the school sample. [For the 2020 report, see ED608768.]