Mass-Observation was a United Kingdom social research organisation founded in 1937. Their work ended in the mid-1960s but was revived in 1981. The Archive is housed at the University of Sussex.
Mass-Observation aimed to record everyday life in Britain through a panel of around 500 untrained volunteer observers who either maintained diaries or replied to open-ended questionnaires (known as directives). They also paid investigators to anonymously record people's conversation and behaviour at work, on the street and at various public occasions including public meetings and sporting and religious events.