Will the questionnaire be self-administered or administered by a research/clinical staff? This decision depends, in part, on what the questionnaire intends to measure. If a questionnaire exists, but only in a different language, the task is to translate and validate the questionnaire in the new language.Äetermine the format in which the questionnaire will be administered If no existing questionnaires are available, or none that are determined to be appropriate, it is appropriate to construct a new questionnaire. Examples of necessary validation processes can be found in the validation section of this paper. The validation processes should have been completed using a representative sample, demonstrating adequate reliability and validity. A validated questionnaire refers to a questionnaire/scale that has been developed to be administered among the intended respondents. Once the construct of interest has been determined, it is important to conduct a literature review to identify if a previously validated questionnaire exists. The next question is: How will the construct be operationalized? In other words, what types of behavior will be indicative of the domain of interest? Several approaches have been suggested to help with this process, such as content analysis, review of research, critical incidents, direct observations, expert judgment, and instruction. It is crucial to identify the construct that is to be assessed with the questionnaire, as the domain of interest will determine what the questionnaire will measure. In this special issue of the Saudi journal of Anesthesia we presented multiple studies of development and validation of questionnaires in perioperative and pain medicine, we encourage readers to refer to them for practical experience. A model for the questionnaire development and translation process is presented in Figure 1. The second section of this paper illustrates procedures to validate the questionnaire after the questionnaire is developed or translated. The first discusses issues that investigators should be aware of in developing or translating a questionnaire. This article is divided into two main sections. Readers are recommended to consult the cited references to further examine these techniques for application. Rather, this article aims to provide straightforward guidelines for the development or translation of questionnaires (or scales) for use in perioperative and pain medicine research for readers who may be unfamiliar with the process of questionnaire development and/or translation. To that end, this article is not meant to provide an exhaustive review of all the related statistical concepts and methods. Prior work has highlighted the wealth of literature available on psychometric principles, methodological concepts, and techniques regarding questionnaire development/translation and validation. As a result, investigators may need to develop a new questionnaire or translate an existing one into the language of the intended respondents. Although using an existing questionnaire will save time and resources, a questionnaire that measures the construct of interest may not be readily available, or the published questionnaire is not available in the language required for the targeted respondents. Data of interest could range from observable information (e.g., presence of lesion, mobility) to patients’ subjective feelings of their current status (e.g., the amount of pain they feel, psychological status). Questionnaires or surveys are widely used in perioperative and pain medicine research to collect quantitative information from both patients and health-care professionals.