This article addresses the comparability of sampling and fieldwork with an analysis of methodological data describing 1,537 national surveys from five major comparative cross-national survey projects in Europe carried out in the period from 1981 to 2017. We describe the variation in the quality of the survey documentation, and in the survey methodologies themselves, focusing on survey procedures with respect to: 1) sampling frames, 2) types of survey samples and sampling designs, 3) within-household selection of target persons in address-based samples, 4) fieldwork execution and 5) fieldwork outcome rates. Our results show substantial differences in sample designs and fieldwork procedures across survey projects, as well as changes within projects over time. This variation invites caution when selecting data for analysis. We conclude with recommendations regarding the use of information about the survey process to select existing survey data for comparative analyses.