In this paper we investigate the representativeness of the LISS panel survey. We compare the characteristics of the panel members of this online survey, based on a probability sample, to national statistics on the total population in the Netherlands. We also provide a comparison with panel data collected in a more traditional manner and with an online access panel. One notable result is that despite the provision of free internet access and/or a PC to households who were not yet online, the elderly are still underrepresented but less so than in an online access panel. In the second part of the paper, the respondents to two individual questionnaires are compared to the total panel and to the national statistics. We provide crosstabulations as well as a multivariate logit analysis of panel participation and response. We find a considerable overlap between the variables associated with differences in the probability to participate in the panel and the probability to respond to two individual questionnaires.