The study investigates how foundational literacy influences online fact-checking behavior among college students, with news literacy acting as a mediator. Findings show that stronger foundational literacy improves fact-checking through enhanced news literacy, but reliance on heuristic (shortcut) thinking weakens this effect. The study highlights the impact of cognitive biases in social media contexts and emphasizes the need for journalism education to integrate critical news literacy, reflective media engagement, and awareness of digital information environments to support responsible digital citizenship.