To better understand who participates in media-driven public discussion and opinion-making, this working paper presents the results of a randomised household survey implemented in four constituencies in Kenya and Zambia, one urban and one rural constituency in each country. The survey was conducted as part of Politics and Interactive Media in Africa (PiMA), a collaborative research project analysing the nature and political implications of expressions of public opinion in broadcast media in Kenya and Zambia, via new information and communication technologies (ICT) such as mobile phones. This paper presents descriptive survey results that are the basis of a deeper comparative analysis of drivers of listenership and participation in interactive broadcast media shows, also published in the PiMA Working Paper series. Nevertheless, a few results are highlighted here. The survey reveals that level of radio listenership of interactive shows in the two Kenyan constituencies is high, particularly in Kenya, ranging between 80-90%, whereas in Zambia listenership levels range between 40-60%, contrasting with listenership to radio shows generally (70-85%). Radio listeners tend to listen to all types of shows, from politics and development shows to social/cultural and music/entertainment shows. Yet country differences in interactive show listenership are not reflected in the levels of participation in interactive radio shows. Both in Kenya and in Zambia, roughly 20% of the total population have participated at one time or another in interactive shows. However, contrasting with listenership, participation tends to be more segmented across types of shows. Rural and urban constituencies show an inverse pattern of participation in Kenya and Zambia, with higher levels of participation in the urban sample from Zambia (21% versus 12% in the rural), and the rural sample from Kenya (21% versus 19% in the urban). Across the four sites, male and more educated listeners are more likely to engage interactive shows. Three to four times more men engage in interactive shows than women. Of the women who participate in interactive shows, they tend to be younger, single, more educated and wealthier compared with those who do not participate. Calling in to the studio is the most frequent form of engagement in radio shows, especially in rural areas. SMS is more popular in urban constituencies, particularly in Kenya. Only 10% of those who have participated in interactive media shows have ever used social media to communicate with stations. Across all sites, the main barriers to participation identified are cost and expectations of not getting through.