This chapter considers some of the key challenges to achieving comparability in deliberately designed cross-cultural and cross-national surveys. As the word challenge reflects, we focus on topics for which theoretical frameworks or current solutions are less than perfect. We spend some time therefore on issues of standardization and implementation, on question design and on question adaptation and translation. Among the topics not dealt with here, but of obvious relevance for comparative survey research, are sampling, analysis, instrument testing, study documentation, and ethical considerations. See Häder and Gabler (2003), Lynn, Häder, Gabler & Laaksonen (2007), Lepkowski (2005) on sampling in cross-national contexts; Saris (2003a, 2003b), Billiet (2003), van de Vijver (2003), and contributions in Hambleton, Merenda, & Spielberger (2005) cover important issues in instrument testing; on documentation see Mohler, Pennell & Hubbard (Chapter 21) and Mohler and Uher (2003) and on ethical considerations see Singer (Chapter 5).