Background: There has been no validated instrument to identify barriers and facilitators to practicing preventive COVID-19 measures. Objectives: The present study aimed to develop and evaluate an instrument to identify facilitators and barriers to practicing COVID-19 preventive measures. Methods: The present study was conducted in two phases from September 2020 to December 2021. In the first phase, the researchers interviewed 20 residents of Sanandaj city, Iran, recruited using the purposive sampling method. Thematic analysis was done to elicit the initial codes from the interview scripts; then, themes were generated to develop the questions. In the second phase, psychometric properties of the test, including face validity, content validity, construct validity, and internal consistency, were investigated among 100 people using an online questionnaire. Afterward, the face, content, and construct validity were investigated through exploratory factor analysis. The entry criterion included people living in Sanandaj city, and the exit criterion was unwillingness to continue cooperation. Results: Participants included nine women and 11 men, with an average age of 28.95 years. After finishing the first phase of the study, 24 statements were generated. They were expanded into 31 statements after reviewing the related literature. The statements were categorized into three classes: adherence to practice, barriers, and facilitators. The results revealed five factors for adherence to practice, two factors for facilitators, and two factors for barriers. The instrument's reliability was reported at 0.91, calculated using Cronbach's alpha. Conclusions: The developed instrument might help investigate barriers and facilitators to practicing COVID-19 preventive measures. The findings may result in developing more effective strategies to promote practicing COVID-19 preventive measures.