Rural teenagers face elevated risks for substance use, delinquency, and other problem behaviors that can derail healthy development into adulthood. Understanding which psychological resources provide the strongest protective effects could reshape prevention strategies for this vulnerable population. A longitudinal study tracking 770 rural Chinese adolescents over one year reveals that internal psychological resilience operates differently than external social support in preventing risky behaviors. The research employed sophisticated statistical modeling to separate stable individual differences from dynamic changes over time. Adolescents who developed stronger psychological capital—encompassing hope, efficacy, resilience, and optimism—showed measurable reductions in problem behaviors within just a few months. This protective effect appeared unidirectional: while stronger psychological resources predicted fewer risk behaviors, engaging in problem behaviors did not subsequently erode these internal strengths. Social support demonstrated a more complex bidirectional relationship. Higher perceived support from family, peers, and community predicted subsequent decreases in problem behaviors, but the relationship worked in reverse as well—teenagers engaging in more risk behaviors experienced declining social support over time, potentially creating a downward spiral. This finding challenges the assumption that social support remains stable regardless of adolescent behavior. The study's strength lies in its ability to track individual changes rather than just comparing different groups. However, the rural Chinese context may limit generalizability to other populations, and the one-year timeframe captures only short-term effects. For youth development programs, these results suggest prioritizing psychological skills training alongside family and community engagement, recognizing that internal resilience may provide more durable protection than external support alone.