In 2004 Germany's Federal Statistical Office (Statistisches Bundesamt, Destatis) started the recruitment of an access panel (AP) from participantes in the German microcensus (MC), a large household survey. This access panel, a pool of persons willing to take part in voluntary surveys, currently serves as the sampling frame for the DE-SILC, the German subsample of the European Union Statistic on Income and Living Conditions. Sampling from panelists rather than directly from the population promised lower survey costs due to easy access to the AP participants and higher response rates. While participation in the MC is mandatory by law, joining the AP is voluntary. Approx. 10 percent of the MC households agree to enter the panel. In this work we examine the recruitment from the 2006 MC using socio-economic and demographic characteristics available in both the AP and the MC to explore the selectivity of the recruitment process. We also discuss the implications of German privacy protection legislation for this analysis. Finally we consider the longitudinal use of the AP in a methodological discussion on the question whether samples from the AP can be regarded as probability samples from the general population.