Social contact survey data forms a core component of modern epidemic models: however, there has been little assessment of the potential biases in such data. We conducted focus groups with university students who had (n = 13) and had never (n = 14) completed a social contact survey during the COVID-19 pandemic. Qualitative findings were explored quantitatively by analysing participation data. The opportunity to contribute to COVID-19 research, to be heard and feel useful were frequently reported motivators for participating in the contact survey. Reductions in survey engagement following lifting of COVID-19 restrictions may have occurred because the research was perceived to be less critical and/or because the participants were busier and had more contacts. Having a high number of contacts to report, uncertainty around how to report each contact, and concerns around confidentiality were identified as factors leading to inaccurate reporting. Focus groups participants thought that financial incentives or provision of study results would encourage participation. Incentives could improve engagement with social contact surveys. Qualitative research can inform the format, timing, and wording of surveys to optimise completion and accuracy. Display omitted •Social contact survey data inform epidemic models, but may have associated biases.•We held focus groups of COVID-19 contact survey participants and non-participants.•Motivators for participation were “being heard” and “feeling useful”.•High contact numbers and uncertainty in reporting led to inaccuracies.•Financial incentives and provision of survey results may encourage participation.