Nonresponse is a recurring problem in household surveys in many countries. Response rates of Statistics Netherlands surveys often vary between 50% and 60%. Research shows that nonresponse is usually selective. Respondents and nonrespondents differ at various demographic characteristics. To avoid a substantial negative impact on the quality of survey results, often weighting adjustment techniques are carried out. Statistics Netherlands has a large amount of background information available for this purpose. This information originates from registers and other administrative sources. The paper describes research aimed at finding auxiliary variables that are most important for including in weighting models. Also a technique is proposed to select the best weighting model. Theory is applied to data from a major survey.