Social policy decisions are often informed by short-term outcomes. This results in ‘firefighting’ instead of long-term prevention. This causes unnecessary suffering. Preventive policies early in life are probably particularly effective, given their lifelong consequences. These long-term effects remain invisible - models to quantify them don’t exist. We make these long-term effects visible, so they can be incorporated in policy decisions. We develop innovative simulation models for this and apply these to two policy cases: free-of-charge contraceptives, and childcare subsidies. Our models can also be applied to other policy domains, contributing to a shift in policy making from ‘firefighting’ to prevention.