This introduction to the following five articles discusses concepts, practices and debates before and after the adoption of the term “questionnaire” in the late nineteenth century. Information gathering by way of itemized questions was established in the early modern period (c. 1500–1700). Developments associated with questionnaires in the modern period (such as mass standardized items) began in the late 1800s; but there was significant scrutiny of the questionnaire itself in the decades between the two World Wars.