A mandatory postal and web survey on education among 218 000 immigrants in Norway was conducted in 2011. This survey is about 100 times the size of a normal postal survey by Statistics Norway. Usually, it is hard to distinguish between those who fail to answer and the letters which are returned unopened by the postal service, so-called non-contacts. The number of non-contacts is usually insignificantly small and is not paid any special attention. The size of this survey gives us a unique opportunity to take a closer look at the non-contact group. The immigrants were sent a letter from Statistics Norway. A number of these belong to the non-contact group. Based on this survey, we are able to run a thorough non-contact analysis. Testing in our registers for, among other things, country of origin, duration of stay, age, sex, reason for immigration and family relationship, we will look for some characteristics of the non-contact immigrants. Our hypothesis is that the quality of the Central Population Register (CPR) varies for different subgroups of the population. This information will be useful for the Norwegian register-based census.