This article describes the key aspects in the design, construction and adaptation of survey questionnaires. There are different types of questionnaire, each of which has its advantages and disadvantages. Aspects of constructing the questionnaire are discussed in detail; choosing the mode of administration; the objectives of the survey; availability of resources; characteristics of the target population; and quality of data. Issues concerning the identification of the questionnaire's content, wording and sequencing of the questions through to the overall appearance and layout of the questionnaire are also considered. Differences in the role of open-ended and closed questions, together with their strengths and weaknesses, are outlined, and the need to undertake pre-testing and piloting as an integral part of questionnaire development is highlighted. Finally, issues around the adaptation of existing questionnaires are discussed with particular emphasis on their use in different language and cultural groups, and the need to achieve conceptual, content, semantic, operational and functional equivalence is described. An overview of the translation process is provided.