EN
When we send advance letters to the sampled persons in a survey, we expect that the recipients will read them and, based on the information provided, will decide on their participation in the survey. Therefore, the letter is expected to play an important role paving the way for the interaction with the interviewer. Findings from in-depth interviews with hard refusers from ESS 3 (2006) and ESS 4 (2008) presented in this paper indicate that such individuals are generally not interested in the mailing received and can hardly remember anything from it. The paper also shows how, following the findings of this research, the advance letters in subsequent ESS rounds in Poland were modified in order to generate recipients’ interest and drive participation.