This document provides information on constructing questionnaires. It defines what a questionnaire is and describes the various types. The key steps outlined for constructing a questionnaire are: writing the study aim, identifying broad topic areas, breaking these into single-item statements, constructing questions and the questionnaire, and validating the questionnaire. Various question types like closed-ended, open-ended, rating scales, and checklists are described. Guidelines are provided for writing clear, unbiased questions and properly structuring the questionnaire. The importance of validation by piloting the questionnaire on a small sample is also covered.