Cyber disinformation is a global, very sophisticated phenomenon, capable of producing negative consequences on democratic values and institutions. This chapter argues that individual behavior of users plays a key role in the control of the phenomenon and aims to identify factors that impact on users’ behavioral intentions and cyber hygiene behavior. This chapter integrates the Extended Theory of Planned Behavior and a Structural Equation Model, realized through Partial Least Square – –Structural Equation Modeling, applied to the cyber disinformation phenomenon. The research data were collected using a questionnaire administered in Poland and Romania and analyzed using the Structural Equation Model. The model’s parameters were processed using the SmartPLS software. The reliability of the variables was assessed using Cronbach’s Alpha and Composite Reliability. The research revealed the applicability of the Theory of Planned Behavior model and found that Moral Norms and Perceived Behavioral Control have an impact on Behavioral Intention and Cyber Hygiene Behavior. The findings of this chapter can provide stakeholders with important insights that can lead to improved responses to the phenomenon.