Chapter 3 characterises the interaction at Prime Minister’s Questions (PMQs) as an institutionalised, parliamentary activity in change, in which members of the House of Commons have engaged since the institutionalisation of PMQs in 1961. It is shown that – due to various extralinguistic factors –PMQs has undergone rapid change during the span of 36 years covered by the study. However, it is argued that the institutional backbone of the activity, i.e. the physical set-up of the Chamber, the mediated question–answer sequences as well as the third-person address system, has remained largely the same, which warrants a comparative perspective on the 1978–1988 and 2003–2013 data sets as representatives of the same activity in different times.