To explore potential effects of disadvantage on engagement and attainment under different teaching and assessment regimes, the influence of pedagogic changes implemented during the COVID-19 pandemic on attainment and engagement of students from different backgrounds were compared using a cohort-study design. Learner analytics and attainment data from first year undergraduate students during three learning regimes were compared: (i) in-person teaching and assessment, (ii) in-person teaching with online assessment, and (iii) online teaching and assessment. The gap in end-of-year mark between disadvantaged students and their peers was widest when teaching and assessment was online, with poorer outcomes for disadvantaged students, although the gap in the percentage of students passing all their modules did not change. Overall, online teaching and assessment during the pandemic was associated with a widening attainment gap between disadvantaged students and their peers. Possible explanations for this are discussed, including the relationship between attainment and engagement. Higher Education providers should monitor and review the potential implications of their chosen education strategy on different groups of students: how you teach and who you teach are both important.