Surveys have become an essential component in health research and are particularly useful when evaluating constructs that require individual self-assessment of knowledge, opinions, attitudes and behaviors. They have a wide accessibility to the target population, especially when this is represented by the general population, they can potentially reach a large sample size and collect large amounts of information in a relatively short time. However, conducting a good quality survey is more complex than it seems. Indeed, the methods used can significantly affect the reliability and generalizability of the results. This dissertation describes the use of survey in three studies aimed at investigating: 1) knowledge of prevention measures, perception of contagion risk and the correlation with training received, including volunteering during the COVID-19 pandemic, among medical students; 2) the attitude of Emilia-Romagna citizens towards vaccination against COVID-19 and the factors associated with hesitation; 3) trust in the healthcare system, perceived quality and use of health services, and how these aspects are linked to each other and to the Italian population’s characteristics. In the final chapter, the three surveys are compared from a methodological point of view, in order to draw useful lessons for a more appropriate application to research in public health. This comparison highlights how survey planning and conduction imply several methodological choices that must consider the research objective as well as timing and available resources. A literature review and the involvement of a multidisciplinary team are key ingredients for planning effective surveys, answering the research question and producing reliable evidence. The estimates provided by the surveys can be used to monitor progresses towards the achievement of health objectives and to identify aspects towards which efforts should be directed.