The chapter aims to introduce the reader to the major stages in questionnaire design and to demonstrate how to choose and develop a questionnaire for a research project. Questionnaires are used in large-scale surveys, such as the British Social Attitudes Survey, as well as in smaller-scale projects, including psychology laboratory classes. Thus the simple questionnaire can be applied at different levels of investigation and different levels of complexity. The function of a questionnaire is to measure something. Thus self- and group-administered questionnaires are generally completed in the presence of an official agent, supervisor, or researcher. Interviews often have a higher response rate than the postal questionnaire. The alternatives given to the respondent in a closed question may take several forms. The most commonly used types of response format are alternate choice items, multiple choice items, and rating scale items. Comprehension of a question is primarily a function of question wording.