The effectiveness of hand hygiene (HH) on reducing the transmission of contagious diseases is widely known, although its use has been commonly associated with the area of healthcare. During the COVID-19 pandemic, HH was one of the main measures established to contain the transmission of this virus. The identification of the main barriers and facilitators of HH in young adults (aged 18–29 years old) will contribute to the better planning of HH training and its posterior success. A total of 716 young adults participated in the study by completing the ad hoc online questionnaire (#YesWeHand), which analyzed, among other aspects, the age range, gender and field of study that they belonged to. From the total participants, 81.3% indicated knowing how to perform HH correctly, while 49.4% affirmed having received training. The main reason for performing HH was concern for their own safety and that of others (75.8%), while forgetfulness (36.5%) was the main reason for not performing HH. In the group of young adults, being female, aged between 22 and 25 years old, and having studied in the area of Health Sciences, had a positive influence on correct HH. It is deemed necessary to maintain HH beyond the primary education stages, and to adapt it to different fields of education, ages, and genders, in order to maximize its success. Given the overrepresentation of participants from the healthcare field, it would be desirable to conduct more studies to ensure a better representation of the different educational levels and fields of study of the participants, in order to identify, in a more reliable way, the variables that influence HH.