This chapter discusses nonresponse from a comparative point of view. It deals with an assessment of the risks of nonresponse bias and possibilities of post-survey adjustment. Special attention will be paid to the availability and characteristics of sampling frames and of paradata that can be collected to evaluate data collection and assess nonresponse bias. The chapter presents a number of major factors in data collection that can have an impact on response rates and nonresponse bias. It describes different harmonization models aimed at minimizing the effect of differences in data collection procedures and traditions across countries. Assuming that survey climate can be measured, the next question is to determine how this climate might impact response rates and, more importantly, nonresponse biases across countries. In cross-national studies the design of a survey can be optimized for individual countries or populations.